<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:c8b5b55e-5374-400e-a80b-995e84b2daa3,g:b508c2b3-86db-4ec2-9c01-90a7c84c0ee2-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/CondensedConsolidatedStatementofEquity" xlink:type="simple" xlink:href="cpix-20250331.xsd#CondensedConsolidatedStatementofEquity"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/CondensedConsolidatedStatementofEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_6f0de78d-b499-42d7-93bf-8d7df4b8b744" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_32049d05-fb3a-4c7e-8ce5-07f1b355c8f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_6f0de78d-b499-42d7-93bf-8d7df4b8b744" xlink:to="loc_us-gaap_StatementTable_32049d05-fb3a-4c7e-8ce5-07f1b355c8f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_20b4949e-5410-4464-ab2a-347343a59c23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_32049d05-fb3a-4c7e-8ce5-07f1b355c8f6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_20b4949e-5410-4464-ab2a-347343a59c23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_20b4949e-5410-4464-ab2a-347343a59c23_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_20b4949e-5410-4464-ab2a-347343a59c23" xlink:to="loc_us-gaap_EquityComponentDomain_20b4949e-5410-4464-ab2a-347343a59c23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_951dbe65-85a6-4133-9a6d-ffcbc83adf18" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_20b4949e-5410-4464-ab2a-347343a59c23" xlink:to="loc_us-gaap_EquityComponentDomain_951dbe65-85a6-4133-9a6d-ffcbc83adf18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_db8ddcfd-07d3-4df8-b033-77c05ab25148" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_951dbe65-85a6-4133-9a6d-ffcbc83adf18" xlink:to="loc_us-gaap_CommonStockMember_db8ddcfd-07d3-4df8-b033-77c05ab25148" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_96131654-5652-4e38-a97d-5c175d2e2793" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_951dbe65-85a6-4133-9a6d-ffcbc83adf18" xlink:to="loc_us-gaap_RetainedEarningsMember_96131654-5652-4e38-a97d-5c175d2e2793" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_ce7c1763-f6a0-48e9-b174-e7e96c466f8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_951dbe65-85a6-4133-9a6d-ffcbc83adf18" xlink:to="loc_us-gaap_NoncontrollingInterestMember_ce7c1763-f6a0-48e9-b174-e7e96c466f8f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6f0de78d-b499-42d7-93bf-8d7df4b8b744" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_3f0eb7e1-f5fd-46df-9190-bec3b049dba6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_3f0eb7e1-f5fd-46df-9190-bec3b049dba6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_c100d830-a981-422e-8c2e-aa6c35a4379c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_c100d830-a981-422e-8c2e-aa6c35a4379c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_b23ebe0d-b0b8-441f-b8cb-14ff47ebde43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_b23ebe0d-b0b8-441f-b8cb-14ff47ebde43" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_c325e092-67c7-4499-9722-4828e9b1545b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_c325e092-67c7-4499-9722-4828e9b1545b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_e5b855a0-be8e-451d-858c-1917601cef1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_e5b855a0-be8e-451d-858c-1917601cef1c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_30f783cd-5dad-473a-9080-1ea899826a3b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_30f783cd-5dad-473a-9080-1ea899826a3b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_73f8866d-1396-4fe3-8065-34a857cf713d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_73f8866d-1396-4fe3-8065-34a857cf713d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_8fdb2676-26d2-4c9d-9c44-2feb4141b95e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_8fdb2676-26d2-4c9d-9c44-2feb4141b95e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_c803eb18-5a49-4faa-8410-c019dfd870ca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_ea287fce-a271-493b-8024-403dad8b23cc" xlink:to="loc_us-gaap_ProfitLoss_c803eb18-5a49-4faa-8410-c019dfd870ca" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_22ef9323-454f-43a3-a45e-4ae9570555b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_4804377b-a8b3-4834-864a-fe1f00288080" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/RevenuesScheduleofNetProductRevenuesbyProductDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#RevenuesScheduleofNetProductRevenuesbyProductDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/RevenuesScheduleofNetProductRevenuesbyProductDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_faa8f72c-e724-4804-a2c8-328a5af4c4e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_3c530493-ac74-4603-82a1-f708679fdd34" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_faa8f72c-e724-4804-a2c8-328a5af4c4e9" xlink:to="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_3c530493-ac74-4603-82a1-f708679fdd34" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_3e908f88-09a7-4b1f-9725-1a09b1f315a3" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_3c530493-ac74-4603-82a1-f708679fdd34" xlink:to="loc_srt_ProductOrServiceAxis_3e908f88-09a7-4b1f-9725-1a09b1f315a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3e908f88-09a7-4b1f-9725-1a09b1f315a3_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_3e908f88-09a7-4b1f-9725-1a09b1f315a3" xlink:to="loc_srt_ProductsAndServicesDomain_3e908f88-09a7-4b1f-9725-1a09b1f315a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_3e908f88-09a7-4b1f-9725-1a09b1f315a3" xlink:to="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductKristaloseMember_408e6d03-06fc-4998-b2f0-4dc078628d88" xlink:href="cpix-20250331.xsd#cpix_ProductKristaloseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductKristaloseMember_408e6d03-06fc-4998-b2f0-4dc078628d88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductSancusoMember_82f6f96f-39d7-45d6-8c11-cbc8f806eb5f" xlink:href="cpix-20250331.xsd#cpix_ProductSancusoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductSancusoMember_82f6f96f-39d7-45d6-8c11-cbc8f806eb5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductVibativMember_1df99801-9464-4eb4-9ba0-68c855c1eacb" xlink:href="cpix-20250331.xsd#cpix_ProductVibativMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductVibativMember_1df99801-9464-4eb4-9ba0-68c855c1eacb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductCaldolorMember_95970b22-7da2-45e0-91bb-90ca73160052" xlink:href="cpix-20250331.xsd#cpix_ProductCaldolorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductCaldolorMember_95970b22-7da2-45e0-91bb-90ca73160052" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductAcetadoteMember_a162320c-d691-4372-89ba-154fa2412093" xlink:href="cpix-20250331.xsd#cpix_ProductAcetadoteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductAcetadoteMember_a162320c-d691-4372-89ba-154fa2412093" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductOmeclamoxPakMember_47eae6d1-551c-4b1a-b86d-7a634ad00530" xlink:href="cpix-20250331.xsd#cpix_ProductOmeclamoxPakMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductOmeclamoxPakMember_47eae6d1-551c-4b1a-b86d-7a634ad00530" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductVaprisolMember_34c0c75e-1732-4b9f-aa1f-3d69e55026d4" xlink:href="cpix-20250331.xsd#cpix_ProductVaprisolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductVaprisolMember_34c0c75e-1732-4b9f-aa1f-3d69e55026d4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductRediTrexMember_2a8ad21a-a746-40f2-92d1-2f710cfe7f72" xlink:href="cpix-20250331.xsd#cpix_ProductRediTrexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductRediTrexMember_2a8ad21a-a746-40f2-92d1-2f710cfe7f72" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductOtherMember_41fd91fe-2c85-4daa-be8f-2be6bee66524" xlink:href="cpix-20250331.xsd#cpix_ProductOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d0a7e613-f604-49f0-92c8-92b1b6ee3e8f" xlink:to="loc_cpix_ProductOtherMember_41fd91fe-2c85-4daa-be8f-2be6bee66524" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e525face-3104-4957-99b0-c513614c011d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_faa8f72c-e724-4804-a2c8-328a5af4c4e9" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e525face-3104-4957-99b0-c513614c011d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_RevenueFromContractWithCustomerExcludingAssessedTaxIncludingAdjustments_1e74c5a2-2bc3-4ad1-9dc3-ecc0f7945326" xlink:href="cpix-20250331.xsd#cpix_RevenueFromContractWithCustomerExcludingAssessedTaxIncludingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_faa8f72c-e724-4804-a2c8-328a5af4c4e9" xlink:to="loc_cpix_RevenueFromContractWithCustomerExcludingAssessedTaxIncludingAdjustments_1e74c5a2-2bc3-4ad1-9dc3-ecc0f7945326" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_3c58ab47-c7a3-4eba-be81-fbc123c90b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_faa8f72c-e724-4804-a2c8-328a5af4c4e9" xlink:to="loc_us-gaap_Revenues_3c58ab47-c7a3-4eba-be81-fbc123c90b8f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/RevenuesNarrativeDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#RevenuesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/RevenuesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_00e10603-8251-4757-92df-7373e4703666" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_7bad249d-bd4f-4d40-a4f5-eab83d8a0f5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_00e10603-8251-4757-92df-7373e4703666" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_7bad249d-bd4f-4d40-a4f5-eab83d8a0f5e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_004872d7-1fd1-40e9-9f3d-490f6fbe3655" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_7bad249d-bd4f-4d40-a4f5-eab83d8a0f5e" xlink:to="loc_srt_ProductOrServiceAxis_004872d7-1fd1-40e9-9f3d-490f6fbe3655" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_004872d7-1fd1-40e9-9f3d-490f6fbe3655_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_004872d7-1fd1-40e9-9f3d-490f6fbe3655" xlink:to="loc_srt_ProductsAndServicesDomain_004872d7-1fd1-40e9-9f3d-490f6fbe3655_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2ca1b9f5-a723-47ae-b0c5-386496ea16f7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_004872d7-1fd1-40e9-9f3d-490f6fbe3655" xlink:to="loc_srt_ProductsAndServicesDomain_2ca1b9f5-a723-47ae-b0c5-386496ea16f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductOmeclamoxPakMember_46a9c0b0-de58-400f-97e1-6c9038515c1f" xlink:href="cpix-20250331.xsd#cpix_ProductOmeclamoxPakMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2ca1b9f5-a723-47ae-b0c5-386496ea16f7" xlink:to="loc_cpix_ProductOmeclamoxPakMember_46a9c0b0-de58-400f-97e1-6c9038515c1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrantMember_0058b27e-aedd-419b-ab5a-bfa891855096" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2ca1b9f5-a723-47ae-b0c5-386496ea16f7" xlink:to="loc_us-gaap_GrantMember_0058b27e-aedd-419b-ab5a-bfa891855096" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductVibativMember_09cb82f1-8574-4aff-b53e-d6c235b08f8a" xlink:href="cpix-20250331.xsd#cpix_ProductVibativMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2ca1b9f5-a723-47ae-b0c5-386496ea16f7" xlink:to="loc_cpix_ProductVibativMember_09cb82f1-8574-4aff-b53e-d6c235b08f8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_745d6c36-e635-49d1-a5da-19488cab7044" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_00e10603-8251-4757-92df-7373e4703666" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_745d6c36-e635-49d1-a5da-19488cab7044" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubleaseIncome_625e837b-5d6c-4973-ab1c-2b063a90051d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubleaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_00e10603-8251-4757-92df-7373e4703666" xlink:to="loc_us-gaap_SubleaseIncome_625e837b-5d6c-4973-ab1c-2b063a90051d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherSellingAndMarketingExpense_c4193377-61af-4ce1-b92a-8f3a3acb9700" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherSellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_00e10603-8251-4757-92df-7373e4703666" xlink:to="loc_us-gaap_OtherSellingAndMarketingExpense_c4193377-61af-4ce1-b92a-8f3a3acb9700" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/InventoriesNarrativeDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#InventoriesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/InventoriesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryLineItems_acc0f7ba-d66c-4e51-9d4b-e0c9d66377ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryCurrentTable_a3d11100-b49d-42b8-b49e-f7d6435b2ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryCurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_InventoryLineItems_acc0f7ba-d66c-4e51-9d4b-e0c9d66377ae" xlink:to="loc_us-gaap_InventoryCurrentTable_a3d11100-b49d-42b8-b49e-f7d6435b2ea9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_06f12e02-5412-42e2-a8ec-c652deee59ab" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_a3d11100-b49d-42b8-b49e-f7d6435b2ea9" xlink:to="loc_srt_ProductOrServiceAxis_06f12e02-5412-42e2-a8ec-c652deee59ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_06f12e02-5412-42e2-a8ec-c652deee59ab_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_06f12e02-5412-42e2-a8ec-c652deee59ab" xlink:to="loc_srt_ProductsAndServicesDomain_06f12e02-5412-42e2-a8ec-c652deee59ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b7943e87-6956-4912-9a5e-74176c0676bb" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_06f12e02-5412-42e2-a8ec-c652deee59ab" xlink:to="loc_srt_ProductsAndServicesDomain_b7943e87-6956-4912-9a5e-74176c0676bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_VibativMember_c1733da2-3d16-4766-bf1e-4abfbabd8157" xlink:href="cpix-20250331.xsd#cpix_VibativMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b7943e87-6956-4912-9a5e-74176c0676bb" xlink:to="loc_cpix_VibativMember_c1733da2-3d16-4766-bf1e-4abfbabd8157" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_65467f0e-54ec-4658-9adb-1cf2a5502173" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_a3d11100-b49d-42b8-b49e-f7d6435b2ea9" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_65467f0e-54ec-4658-9adb-1cf2a5502173" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_65467f0e-54ec-4658-9adb-1cf2a5502173_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_65467f0e-54ec-4658-9adb-1cf2a5502173" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_65467f0e-54ec-4658-9adb-1cf2a5502173_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_05f7b7bd-2ea7-4552-b7c4-0875b2fc06a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_65467f0e-54ec-4658-9adb-1cf2a5502173" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_05f7b7bd-2ea7-4552-b7c4-0875b2fc06a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ActivePharmaceuticalIngredientAPIAndWorkInProgressMember_79f61bae-1127-453f-a8b1-f537dc72c813" xlink:href="cpix-20250331.xsd#cpix_ActivePharmaceuticalIngredientAPIAndWorkInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_05f7b7bd-2ea7-4552-b7c4-0875b2fc06a3" xlink:to="loc_cpix_ActivePharmaceuticalIngredientAPIAndWorkInProgressMember_79f61bae-1127-453f-a8b1-f537dc72c813" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNoncurrent_f6f890d8-cbfb-4f0f-b004-654287a9890c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_acc0f7ba-d66c-4e51-9d4b-e0c9d66377ae" xlink:to="loc_us-gaap_InventoryNoncurrent_f6f890d8-cbfb-4f0f-b004-654287a9890c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/InventoriesScheduleofNonCurrentInventoriesDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#InventoriesScheduleofNonCurrentInventoriesDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/InventoriesScheduleofNonCurrentInventoriesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_cpix_InventoryNoncurrentLineItems_60d5d15f-b709-41fb-9dca-fdb5d18fb781" xlink:href="cpix-20250331.xsd#cpix_InventoryNoncurrentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_InventoryNoncurrentTable_574bab61-f5c9-470b-87f4-4a02826299f9" xlink:href="cpix-20250331.xsd#cpix_InventoryNoncurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cpix_InventoryNoncurrentLineItems_60d5d15f-b709-41fb-9dca-fdb5d18fb781" xlink:to="loc_cpix_InventoryNoncurrentTable_574bab61-f5c9-470b-87f4-4a02826299f9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_9cd51001-9966-4503-9d6c-d57a467a7a24" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cpix_InventoryNoncurrentTable_574bab61-f5c9-470b-87f4-4a02826299f9" xlink:to="loc_srt_ProductOrServiceAxis_9cd51001-9966-4503-9d6c-d57a467a7a24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_9cd51001-9966-4503-9d6c-d57a467a7a24_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_9cd51001-9966-4503-9d6c-d57a467a7a24" xlink:to="loc_srt_ProductsAndServicesDomain_9cd51001-9966-4503-9d6c-d57a467a7a24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_9cd51001-9966-4503-9d6c-d57a467a7a24" xlink:to="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_VibativMember_05647fc5-b7ea-4064-9b33-7a020c38e2fb" xlink:href="cpix-20250331.xsd#cpix_VibativMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_VibativMember_05647fc5-b7ea-4064-9b33-7a020c38e2fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_KristaloseMember_213e807b-0cdc-42dd-93b7-6c0b724b1f28" xlink:href="cpix-20250331.xsd#cpix_KristaloseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_KristaloseMember_213e807b-0cdc-42dd-93b7-6c0b724b1f28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_VaprisolMember_7e2d4936-54a0-4894-97ce-e97dd2a20cf4" xlink:href="cpix-20250331.xsd#cpix_VaprisolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_VaprisolMember_7e2d4936-54a0-4894-97ce-e97dd2a20cf4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_SancusoMember_abe3bb6f-5e63-4fb6-a7e1-ff4ebf4bf232" xlink:href="cpix-20250331.xsd#cpix_SancusoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_SancusoMember_abe3bb6f-5e63-4fb6-a7e1-ff4ebf4bf232" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_CaldolorMember_0e75446d-0788-4568-8f24-4cef38b81555" xlink:href="cpix-20250331.xsd#cpix_CaldolorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_CaldolorMember_0e75446d-0788-4568-8f24-4cef38b81555" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_AcetadoteMember_5bc7eac1-90cc-4179-952e-a899f53d7161" xlink:href="cpix-20250331.xsd#cpix_AcetadoteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_AcetadoteMember_5bc7eac1-90cc-4179-952e-a899f53d7161" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_IfetrobanMember_9cfe871c-1d4b-4c2c-8ef9-f8d0cf3938cc" xlink:href="cpix-20250331.xsd#cpix_IfetrobanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_IfetrobanMember_9cfe871c-1d4b-4c2c-8ef9-f8d0cf3938cc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_OmeclamoxMember_2d462d41-53f0-41bb-9b00-1bec2be254c4" xlink:href="cpix-20250331.xsd#cpix_OmeclamoxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b88a38ba-4aaf-47ee-bb5f-9db3a3284910" xlink:to="loc_cpix_OmeclamoxMember_2d462d41-53f0-41bb-9b00-1bec2be254c4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_d23874dd-ccaa-4ebe-ac8f-6e3d025fe7f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cpix_InventoryNoncurrentTable_574bab61-f5c9-470b-87f4-4a02826299f9" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_d23874dd-ccaa-4ebe-ac8f-6e3d025fe7f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_d23874dd-ccaa-4ebe-ac8f-6e3d025fe7f2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_d23874dd-ccaa-4ebe-ac8f-6e3d025fe7f2" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_d23874dd-ccaa-4ebe-ac8f-6e3d025fe7f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_c43f4370-ded0-40a1-b101-270ae135d9d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_d23874dd-ccaa-4ebe-ac8f-6e3d025fe7f2" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_c43f4370-ded0-40a1-b101-270ae135d9d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryRawMaterialsMember_e1adafeb-bc24-4965-b9ee-55e192ccbe49" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesInventoryRawMaterialsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_c43f4370-ded0-40a1-b101-270ae135d9d3" xlink:to="loc_us-gaap_PublicUtilitiesInventoryRawMaterialsMember_e1adafeb-bc24-4965-b9ee-55e192ccbe49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_FinishedGoodsMember_d5e0cf89-7b59-44d0-bc19-71403f36aa88" xlink:href="cpix-20250331.xsd#cpix_FinishedGoodsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_c43f4370-ded0-40a1-b101-270ae135d9d3" xlink:to="loc_cpix_FinishedGoodsMember_d5e0cf89-7b59-44d0-bc19-71403f36aa88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNoncurrent_60e96dfa-88e5-4f80-9102-471db6811c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cpix_InventoryNoncurrentLineItems_60d5d15f-b709-41fb-9dca-fdb5d18fb781" xlink:to="loc_us-gaap_InventoryNoncurrent_60e96dfa-88e5-4f80-9102-471db6811c7b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_e196055c-bf2f-4b30-9e45-f3105a09c03e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_e196055c-bf2f-4b30-9e45-f3105a09c03e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5b2ac607-5a80-426b-8392-c5ab1b63de1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e196055c-bf2f-4b30-9e45-f3105a09c03e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5b2ac607-5a80-426b-8392-c5ab1b63de1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5b2ac607-5a80-426b-8392-c5ab1b63de1f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5b2ac607-5a80-426b-8392-c5ab1b63de1f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5b2ac607-5a80-426b-8392-c5ab1b63de1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_31ca58cb-14e8-489d-a9ed-b8e2e731b25f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5b2ac607-5a80-426b-8392-c5ab1b63de1f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_31ca58cb-14e8-489d-a9ed-b8e2e731b25f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficeBuildingMember_37263d1a-d005-49f9-b9ed-3f70ae62d4ff" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OfficeBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_31ca58cb-14e8-489d-a9ed-b8e2e731b25f" xlink:to="loc_srt_OfficeBuildingMember_37263d1a-d005-49f9-b9ed-3f70ae62d4ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermAxis_6000da92-4de3-4753-9759-26d9951ca298" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseContractualTermAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e196055c-bf2f-4b30-9e45-f3105a09c03e" xlink:to="loc_us-gaap_LeaseContractualTermAxis_6000da92-4de3-4753-9759-26d9951ca298" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_6000da92-4de3-4753-9759-26d9951ca298_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LeaseContractualTermAxis_6000da92-4de3-4753-9759-26d9951ca298" xlink:to="loc_us-gaap_LeaseContractualTermDomain_6000da92-4de3-4753-9759-26d9951ca298_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_eea00f90-2717-439e-9400-a3486df6ebd7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LeaseContractualTermAxis_6000da92-4de3-4753-9759-26d9951ca298" xlink:to="loc_us-gaap_LeaseContractualTermDomain_eea00f90-2717-439e-9400-a3486df6ebd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_BroadwestLeaseFiveYearRenewalOptionMember_21da10b5-a5aa-4ae3-b9e1-24bef4e354c6" xlink:href="cpix-20250331.xsd#cpix_BroadwestLeaseFiveYearRenewalOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseContractualTermDomain_eea00f90-2717-439e-9400-a3486df6ebd7" xlink:to="loc_cpix_BroadwestLeaseFiveYearRenewalOptionMember_21da10b5-a5aa-4ae3-b9e1-24bef4e354c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_256f54b0-6ccf-441a-bbc6-341d443f92b2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e196055c-bf2f-4b30-9e45-f3105a09c03e" xlink:to="loc_srt_CounterpartyNameAxis_256f54b0-6ccf-441a-bbc6-341d443f92b2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_256f54b0-6ccf-441a-bbc6-341d443f92b2_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_256f54b0-6ccf-441a-bbc6-341d443f92b2" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_256f54b0-6ccf-441a-bbc6-341d443f92b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2d8cadd-8563-4db6-b88c-65f1972ffbfa" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_256f54b0-6ccf-441a-bbc6-341d443f92b2" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2d8cadd-8563-4db6-b88c-65f1972ffbfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_NephronPharmaceuticalsCorporationNephronMember_356e4481-52a6-4ea9-8b4f-52cb1c8d3eb6" xlink:href="cpix-20250331.xsd#cpix_NephronPharmaceuticalsCorporationNephronMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2d8cadd-8563-4db6-b88c-65f1972ffbfa" xlink:to="loc_cpix_NephronPharmaceuticalsCorporationNephronMember_356e4481-52a6-4ea9-8b4f-52cb1c8d3eb6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_KindosMember_0ce8b122-cefb-452d-b01d-b2372e5cd160" xlink:href="cpix-20250331.xsd#cpix_KindosMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2d8cadd-8563-4db6-b88c-65f1972ffbfa" xlink:to="loc_cpix_KindosMember_0ce8b122-cefb-452d-b01d-b2372e5cd160" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_LesseeOperatingLeaseLeasedArea_bb4077f7-47bf-44e4-87e1-92a789147dcf" xlink:href="cpix-20250331.xsd#cpix_LesseeOperatingLeaseLeasedArea"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_cpix_LesseeOperatingLeaseLeasedArea_bb4077f7-47bf-44e4-87e1-92a789147dcf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_b2e49052-5bb9-4041-9090-8251eee5e6a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_b2e49052-5bb9-4041-9090-8251eee5e6a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_LesseeOperatingLeaseNumberOfRenewalTerms_95c0f267-87df-4bd1-a630-929305cae32a" xlink:href="cpix-20250331.xsd#cpix_LesseeOperatingLeaseNumberOfRenewalTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_cpix_LesseeOperatingLeaseNumberOfRenewalTerms_95c0f267-87df-4bd1-a630-929305cae32a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_1532a76d-5d9e-4428-a696-a997eeb2493a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_1532a76d-5d9e-4428-a696-a997eeb2493a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_LesseeOperatingLeaseBaseRent_e66ceb4c-e052-4440-9ea4-1f68c021daa6" xlink:href="cpix-20250331.xsd#cpix_LesseeOperatingLeaseBaseRent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_cpix_LesseeOperatingLeaseBaseRent_e66ceb4c-e052-4440-9ea4-1f68c021daa6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_LesseeOperatingLeaseRentIncrease_21523eed-03b2-4223-a670-4aaa7807d062" xlink:href="cpix-20250331.xsd#cpix_LesseeOperatingLeaseRentIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_cpix_LesseeOperatingLeaseRentIncrease_21523eed-03b2-4223-a670-4aaa7807d062" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_ccfff448-9292-4aed-9861-baa045da3fd4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_ccfff448-9292-4aed-9861-baa045da3fd4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_f4943518-5631-445a-be1c-9346bf9318b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_f4943518-5631-445a-be1c-9346bf9318b2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_30368ed6-ff36-47cc-a96e-04790f992e65" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_30368ed6-ff36-47cc-a96e-04790f992e65" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_7fabe52f-6862-48ed-a520-9277047fd149" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_7fabe52f-6862-48ed-a520-9277047fd149" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_6fbf16fd-532e-4ddb-bfed-29e4cdab582b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_6fbf16fd-532e-4ddb-bfed-29e4cdab582b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_58c62e5c-c3ec-4147-8175-ea6d49cda650" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0011fc58-4518-484a-9ef0-56b15cc4af79" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_58c62e5c-c3ec-4147-8175-ea6d49cda650" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/ShareholdersEquityandDebtDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#ShareholdersEquityandDebtDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/ShareholdersEquityandDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_be5e19f6-232b-440c-81f9-3e14b76daaec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_be5e19f6-232b-440c-81f9-3e14b76daaec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_be5e19f6-232b-440c-81f9-3e14b76daaec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_be5e19f6-232b-440c-81f9-3e14b76daaec" xlink:to="loc_us-gaap_EquityComponentDomain_be5e19f6-232b-440c-81f9-3e14b76daaec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0715e0b6-7611-4e07-a5d4-2a5817d4e525" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_be5e19f6-232b-440c-81f9-3e14b76daaec" xlink:to="loc_us-gaap_EquityComponentDomain_0715e0b6-7611-4e07-a5d4-2a5817d4e525" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_7d89f64c-4d7d-47bf-ac8b-ecccb26a2147" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0715e0b6-7611-4e07-a5d4-2a5817d4e525" xlink:to="loc_us-gaap_CommonStockMember_7d89f64c-4d7d-47bf-ac8b-ecccb26a2147" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_47501dbe-ea2f-4833-ba49-6a8a823f923f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_AwardTypeAxis_47501dbe-ea2f-4833-ba49-6a8a823f923f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_47501dbe-ea2f-4833-ba49-6a8a823f923f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_47501dbe-ea2f-4833-ba49-6a8a823f923f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_47501dbe-ea2f-4833-ba49-6a8a823f923f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ed4e471d-3140-4ad9-ad36-cf05e1f60c27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_47501dbe-ea2f-4833-ba49-6a8a823f923f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ed4e471d-3140-4ad9-ad36-cf05e1f60c27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_8e3c7fa8-1eec-4bed-9ae9-4075dcd8c331" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ed4e471d-3140-4ad9-ad36-cf05e1f60c27" xlink:to="loc_us-gaap_RestrictedStockMember_8e3c7fa8-1eec-4bed-9ae9-4075dcd8c331" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_IncentiveStockOptionsMember_cc827bf7-a14d-4ae0-b2f6-31070132e59f" xlink:href="cpix-20250331.xsd#cpix_IncentiveStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ed4e471d-3140-4ad9-ad36-cf05e1f60c27" xlink:to="loc_cpix_IncentiveStockOptionsMember_cc827bf7-a14d-4ae0-b2f6-31070132e59f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ForfeituredMember_51da88b8-6d9c-49b3-bd92-1cdfae040863" xlink:href="cpix-20250331.xsd#cpix_ForfeituredMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ed4e471d-3140-4ad9-ad36-cf05e1f60c27" xlink:to="loc_cpix_ForfeituredMember_51da88b8-6d9c-49b3-bd92-1cdfae040863" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_b97f5d7a-f290-40d8-b8d5-fa7b51870766" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_srt_TitleOfIndividualAxis_b97f5d7a-f290-40d8-b8d5-fa7b51870766" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b97f5d7a-f290-40d8-b8d5-fa7b51870766_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_b97f5d7a-f290-40d8-b8d5-fa7b51870766" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b97f5d7a-f290-40d8-b8d5-fa7b51870766_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6538ed21-d169-43ef-b338-fb03d8e76909" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_b97f5d7a-f290-40d8-b8d5-fa7b51870766" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6538ed21-d169-43ef-b338-fb03d8e76909" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_1efbcace-383f-4bf1-8b77-a03412d7b881" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6538ed21-d169-43ef-b338-fb03d8e76909" xlink:to="loc_srt_DirectorMember_1efbcace-383f-4bf1-8b77-a03412d7b881" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_3042c851-4c92-4ce3-93fd-71e957893ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_CreditFacilityAxis_3042c851-4c92-4ce3-93fd-71e957893ec2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_3042c851-4c92-4ce3-93fd-71e957893ec2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_3042c851-4c92-4ce3-93fd-71e957893ec2" xlink:to="loc_us-gaap_CreditFacilityDomain_3042c851-4c92-4ce3-93fd-71e957893ec2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_11f76977-38dc-4bec-9845-4c8708fc1500" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_3042c851-4c92-4ce3-93fd-71e957893ec2" xlink:to="loc_us-gaap_CreditFacilityDomain_11f76977-38dc-4bec-9845-4c8708fc1500" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_04d7d802-a030-4107-8b2a-11187fee4993" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_11f76977-38dc-4bec-9845-4c8708fc1500" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_04d7d802-a030-4107-8b2a-11187fee4993" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_75a56fd3-3696-4067-9aa8-53d611a7d746" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_75a56fd3-3696-4067-9aa8-53d611a7d746" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_75a56fd3-3696-4067-9aa8-53d611a7d746_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_75a56fd3-3696-4067-9aa8-53d611a7d746" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_75a56fd3-3696-4067-9aa8-53d611a7d746_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_8e64d04f-e537-4439-9f3f-0a36ceba9a63" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_75a56fd3-3696-4067-9aa8-53d611a7d746" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_8e64d04f-e537-4439-9f3f-0a36ceba9a63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_PinnacleBankMember_dda4d5a2-fcc9-429d-8cb9-619c7fae42ce" xlink:href="cpix-20250331.xsd#cpix_PinnacleBankMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_8e64d04f-e537-4439-9f3f-0a36ceba9a63" xlink:to="loc_cpix_PinnacleBankMember_dda4d5a2-fcc9-429d-8cb9-619c7fae42ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_b2c7f6e5-04c1-457a-9cb9-6fbcd27f51c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_DebtInstrumentAxis_b2c7f6e5-04c1-457a-9cb9-6fbcd27f51c5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b2c7f6e5-04c1-457a-9cb9-6fbcd27f51c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_b2c7f6e5-04c1-457a-9cb9-6fbcd27f51c5" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b2c7f6e5-04c1-457a-9cb9-6fbcd27f51c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e55a401c-09fe-4397-8c06-6b5f37e5c331" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_b2c7f6e5-04c1-457a-9cb9-6fbcd27f51c5" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e55a401c-09fe-4397-8c06-6b5f37e5c331" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_dad7cc8d-0b17-4652-9cf4-b588074b6f41" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e55a401c-09fe-4397-8c06-6b5f37e5c331" xlink:to="loc_us-gaap_LineOfCreditMember_dad7cc8d-0b17-4652-9cf4-b588074b6f41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_c2c236ed-b99d-41a7-8929-76955a205e1a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_srt_CounterpartyNameAxis_c2c236ed-b99d-41a7-8929-76955a205e1a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2c236ed-b99d-41a7-8929-76955a205e1a_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_c2c236ed-b99d-41a7-8929-76955a205e1a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2c236ed-b99d-41a7-8929-76955a205e1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_cfc35395-0ec6-4efa-9cc1-03796469e05d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_c2c236ed-b99d-41a7-8929-76955a205e1a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_cfc35395-0ec6-4efa-9cc1-03796469e05d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_WinHealthInvestmentSingaporeLtdMember_6bbfa811-cf6a-4d3b-8e98-dcd80fc6123b" xlink:href="cpix-20250331.xsd#cpix_WinHealthInvestmentSingaporeLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_cfc35395-0ec6-4efa-9cc1-03796469e05d" xlink:to="loc_cpix_WinHealthInvestmentSingaporeLtdMember_6bbfa811-cf6a-4d3b-8e98-dcd80fc6123b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_59358fab-b107-46c3-84f4-ec4aa2024a51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_59358fab-b107-46c3-84f4-ec4aa2024a51" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_59358fab-b107-46c3-84f4-ec4aa2024a51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_59358fab-b107-46c3-84f4-ec4aa2024a51" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_59358fab-b107-46c3-84f4-ec4aa2024a51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_617e3fc6-e5a7-42e6-b72f-48a449294442" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_59358fab-b107-46c3-84f4-ec4aa2024a51" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_617e3fc6-e5a7-42e6-b72f-48a449294442" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_038b0c48-bd80-4c5b-8ed3-e619d0ba339a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_617e3fc6-e5a7-42e6-b72f-48a449294442" xlink:to="loc_us-gaap_ConvertibleDebtMember_038b0c48-bd80-4c5b-8ed3-e619d0ba339a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_bfb3bd52-eea6-4f53-9c07-59c213e4b3c3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f1ba1427-4582-4437-b7dc-5e16b2681061" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_bfb3bd52-eea6-4f53-9c07-59c213e4b3c3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_bfb3bd52-eea6-4f53-9c07-59c213e4b3c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_bfb3bd52-eea6-4f53-9c07-59c213e4b3c3" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_bfb3bd52-eea6-4f53-9c07-59c213e4b3c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_27ccfea2-0682-46a2-8bbf-4dd872088d84" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_bfb3bd52-eea6-4f53-9c07-59c213e4b3c3" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_27ccfea2-0682-46a2-8bbf-4dd872088d84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_76d454c7-52a0-4368-9be7-f3996213ef8b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_27ccfea2-0682-46a2-8bbf-4dd872088d84" xlink:to="loc_us-gaap_SubsequentEventMember_76d454c7-52a0-4368-9be7-f3996213ef8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_623f8229-0ea4-46cf-a65c-e2c4415ace2f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_623f8229-0ea4-46cf-a65c-e2c4415ace2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_99a90a28-368c-488a-bb57-a4d877968d6a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_99a90a28-368c-488a-bb57-a4d877968d6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_fc56a4c5-b5da-49dc-8820-ebaab0415afd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_fc56a4c5-b5da-49dc-8820-ebaab0415afd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward_98d7c30d-1648-4aa7-9c85-b832521ceeb0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward_98d7c30d-1648-4aa7-9c85-b832521ceeb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_4c0b74f1-726a-4d7b-a5bc-42d9b5732869" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_4c0b74f1-726a-4d7b-a5bc-42d9b5732869" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_StockIssuedDuringPeriodShelfRegistrationProceedsFromSaleOfCorporateSecurities_5cf6ea58-4612-4b51-97cd-662a4e56c3cc" xlink:href="cpix-20250331.xsd#cpix_StockIssuedDuringPeriodShelfRegistrationProceedsFromSaleOfCorporateSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_cpix_StockIssuedDuringPeriodShelfRegistrationProceedsFromSaleOfCorporateSecurities_5cf6ea58-4612-4b51-97cd-662a4e56c3cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_dec6af79-f320-4fde-82a3-a95a45a9dd17" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_dec6af79-f320-4fde-82a3-a95a45a9dd17" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_067a0be4-8537-43b4-a8d1-a6b7222f6d43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_067a0be4-8537-43b4-a8d1-a6b7222f6d43" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_55a6ca60-d25d-4551-a596-ef55dd4c3496" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_55a6ca60-d25d-4551-a596-ef55dd4c3496" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_84bb6ea9-b078-484d-a513-adcb6b5f7060" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_84bb6ea9-b078-484d-a513-adcb6b5f7060" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_LineOfCreditFacilityAdditionalBorrowingCapacity_91eb8a83-0794-4cb6-bd32-a81719efc088" xlink:href="cpix-20250331.xsd#cpix_LineOfCreditFacilityAdditionalBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_cpix_LineOfCreditFacilityAdditionalBorrowingCapacity_91eb8a83-0794-4cb6-bd32-a81719efc088" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityExpirationPeriod_8b953770-71e8-42c0-bb15-b3d9a05bbb07" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_LineOfCreditFacilityExpirationPeriod_8b953770-71e8-42c0-bb15-b3d9a05bbb07" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_37a040b7-11b6-4c4d-8283-4afb31b88394" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_37a040b7-11b6-4c4d-8283-4afb31b88394" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermLineOfCredit_7a82898f-bc72-4971-a327-e8f5e8060b7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermLineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_LongTermLineOfCredit_7a82898f-bc72-4971-a327-e8f5e8060b7b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_e02428aa-ecfb-4ca8-b4b4-52e1eaaca134" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_e02428aa-ecfb-4ca8-b4b4-52e1eaaca134" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_832a7db9-5b14-4cf1-9117-2a0825ac2707" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_832a7db9-5b14-4cf1-9117-2a0825ac2707" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_9e708e5c-b9a5-4690-8111-09842a7cfe7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_9e708e5c-b9a5-4690-8111-09842a7cfe7b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_GrossProceedOfATMShareIssuance_3aec18e6-981f-469b-a2b4-7bb46f84905f" xlink:href="cpix-20250331.xsd#cpix_GrossProceedOfATMShareIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_cpix_GrossProceedOfATMShareIssuance_3aec18e6-981f-469b-a2b4-7bb46f84905f" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOfferingCosts_b5827e7a-3f06-48a0-93e1-71b55c0e9f59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredOfferingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c16023be-26e6-49e8-ade5-8d551f8c9411" xlink:to="loc_us-gaap_DeferredOfferingCosts_b5827e7a-3f06-48a0-93e1-71b55c0e9f59" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_4674c107-4baf-4a3b-96ec-8b2e94de9541" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_361cfd59-f535-4f6f-b6cc-6f991977642b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_4674c107-4baf-4a3b-96ec-8b2e94de9541" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_361cfd59-f535-4f6f-b6cc-6f991977642b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_65111a9c-a9e7-463e-a0b0-e766cac0aaae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_361cfd59-f535-4f6f-b6cc-6f991977642b" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_65111a9c-a9e7-463e-a0b0-e766cac0aaae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_65111a9c-a9e7-463e-a0b0-e766cac0aaae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_65111a9c-a9e7-463e-a0b0-e766cac0aaae" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_65111a9c-a9e7-463e-a0b0-e766cac0aaae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_0178e572-0f42-46ae-8470-8511f10ac5d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_65111a9c-a9e7-463e-a0b0-e766cac0aaae" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_0178e572-0f42-46ae-8470-8511f10ac5d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_9ea46e1c-189b-4cd4-93e2-4eed89abf824" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_0178e572-0f42-46ae-8470-8511f10ac5d5" xlink:to="loc_us-gaap_DomesticCountryMember_9ea46e1c-189b-4cd4-93e2-4eed89abf824" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_b3d21f87-29d5-4a43-82a6-301e7f5d2d2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_4674c107-4baf-4a3b-96ec-8b2e94de9541" xlink:to="loc_us-gaap_OperatingLossCarryforwards_b3d21f87-29d5-4a43-82a6-301e7f5d2d2a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/ProductAcquisitionsAndReturnOfProductRightsNarrativeDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#ProductAcquisitionsAndReturnOfProductRightsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/ProductAcquisitionsAndReturnOfProductRightsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_321795fd-7ddd-4d37-acf4-3b16b68ae9e6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_321795fd-7ddd-4d37-acf4-3b16b68ae9e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_26b170fa-6c4d-4b03-a8e7-d9b63f9d277d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_321795fd-7ddd-4d37-acf4-3b16b68ae9e6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_26b170fa-6c4d-4b03-a8e7-d9b63f9d277d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26b170fa-6c4d-4b03-a8e7-d9b63f9d277d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_26b170fa-6c4d-4b03-a8e7-d9b63f9d277d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26b170fa-6c4d-4b03-a8e7-d9b63f9d277d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_97f168af-161b-4309-95a0-2493675b6e59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_26b170fa-6c4d-4b03-a8e7-d9b63f9d277d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_97f168af-161b-4309-95a0-2493675b6e59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductAssetsAndGlobalRightsVibativMember_f14afbd5-81b9-442d-b68f-373feef4cd6e" xlink:href="cpix-20250331.xsd#cpix_ProductAssetsAndGlobalRightsVibativMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_97f168af-161b-4309-95a0-2493675b6e59" xlink:to="loc_cpix_ProductAssetsAndGlobalRightsVibativMember_f14afbd5-81b9-442d-b68f-373feef4cd6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_U.S.ProductAssetRightsSancusoMember_9d694e57-86fc-4a8b-b3ec-f71ade61be42" xlink:href="cpix-20250331.xsd#cpix_U.S.ProductAssetRightsSancusoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_97f168af-161b-4309-95a0-2493675b6e59" xlink:to="loc_cpix_U.S.ProductAssetRightsSancusoMember_9d694e57-86fc-4a8b-b3ec-f71ade61be42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_da68231a-4361-4c1f-9b6a-3d95e521d716" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_321795fd-7ddd-4d37-acf4-3b16b68ae9e6" xlink:to="loc_srt_RangeAxis_da68231a-4361-4c1f-9b6a-3d95e521d716" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_da68231a-4361-4c1f-9b6a-3d95e521d716_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_da68231a-4361-4c1f-9b6a-3d95e521d716" xlink:to="loc_srt_RangeMember_da68231a-4361-4c1f-9b6a-3d95e521d716_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_2a93abff-62fc-4112-96b0-b121e7c03994" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_da68231a-4361-4c1f-9b6a-3d95e521d716" xlink:to="loc_srt_RangeMember_2a93abff-62fc-4112-96b0-b121e7c03994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c71c182d-c1aa-45ff-aaad-f67943b6b228" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2a93abff-62fc-4112-96b0-b121e7c03994" xlink:to="loc_srt_MaximumMember_c71c182d-c1aa-45ff-aaad-f67943b6b228" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_831325e2-88b9-4c3a-aeb0-eb76b2f379d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_831325e2-88b9-4c3a-aeb0-eb76b2f379d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_PaymentsToAcquireBusinessMilestonePayment_f74c8252-84a2-4ef2-8334-bd6128561c5b" xlink:href="cpix-20250331.xsd#cpix_PaymentsToAcquireBusinessMilestonePayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_cpix_PaymentsToAcquireBusinessMilestonePayment_f74c8252-84a2-4ef2-8334-bd6128561c5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_PaymentsToAcquireBusinessTieredRoyaltyPaymentsPercentage_00833c42-73af-46ef-9815-630d82eeac33" xlink:href="cpix-20250331.xsd#cpix_PaymentsToAcquireBusinessTieredRoyaltyPaymentsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_cpix_PaymentsToAcquireBusinessTieredRoyaltyPaymentsPercentage_00833c42-73af-46ef-9815-630d82eeac33" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_PaymentsToAcquireBusinessTieredRoyaltyPaymentsThreshold_d6d28bdd-fcab-464f-8303-e21ba14ca169" xlink:href="cpix-20250331.xsd#cpix_PaymentsToAcquireBusinessTieredRoyaltyPaymentsThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_cpix_PaymentsToAcquireBusinessTieredRoyaltyPaymentsThreshold_d6d28bdd-fcab-464f-8303-e21ba14ca169" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_074f1290-f8c4-459b-aced-01265730746f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_074f1290-f8c4-459b-aced-01265730746f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_04c23dea-7269-4105-8ced-40faa727c3f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_04c23dea-7269-4105-8ced-40faa727c3f5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_d39ec49a-ab1a-410b-9661-cad0571442eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_d39ec49a-ab1a-410b-9661-cad0571442eb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_PaymentsToAcquireBusinessMilestonePaymentRemaining_b4188da7-c5ae-4cb6-b88f-6a65a5521daf" xlink:href="cpix-20250331.xsd#cpix_PaymentsToAcquireBusinessMilestonePaymentRemaining"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_29d91bf6-66c5-4053-bfbf-23e8c83a98c3" xlink:to="loc_cpix_PaymentsToAcquireBusinessMilestonePaymentRemaining_b4188da7-c5ae-4cb6-b88f-6a65a5521daf" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/ProductAcquisitionsAndReturnOfProductRightsChangeinConsiderationVibativDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#ProductAcquisitionsAndReturnOfProductRightsChangeinConsiderationVibativDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/ProductAcquisitionsAndReturnOfProductRightsChangeinConsiderationVibativDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_05784fd8-0335-45fa-8b6e-3f171c7cb968" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7eb11980-c366-4875-a088-571ba0f56bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_05784fd8-0335-45fa-8b6e-3f171c7cb968" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7eb11980-c366-4875-a088-571ba0f56bdc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d57ec3c6-9aa5-495e-85ac-f4b4219343d8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7eb11980-c366-4875-a088-571ba0f56bdc" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d57ec3c6-9aa5-495e-85ac-f4b4219343d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d57ec3c6-9aa5-495e-85ac-f4b4219343d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d57ec3c6-9aa5-495e-85ac-f4b4219343d8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d57ec3c6-9aa5-495e-85ac-f4b4219343d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_aa185b62-bc42-427a-9f6e-75542838bdae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d57ec3c6-9aa5-495e-85ac-f4b4219343d8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_aa185b62-bc42-427a-9f6e-75542838bdae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_ProductAssetsAndGlobalRightsVibativMember_3ec1be56-63cf-4dc2-8ef9-6988925ea37b" xlink:href="cpix-20250331.xsd#cpix_ProductAssetsAndGlobalRightsVibativMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_aa185b62-bc42-427a-9f6e-75542838bdae" xlink:to="loc_cpix_ProductAssetsAndGlobalRightsVibativMember_3ec1be56-63cf-4dc2-8ef9-6988925ea37b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualRollForward_09c5a85c-76a3-4c54-8bde-5df28173f24f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyAccrualRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_05784fd8-0335-45fa-8b6e-3f171c7cb968" xlink:to="loc_us-gaap_LossContingencyAccrualRollForward_09c5a85c-76a3-4c54-8bde-5df28173f24f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_2dee9eb1-fc22-4105-8a29-c76cd022586a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_09c5a85c-76a3-4c54-8bde-5df28173f24f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_2dee9eb1-fc22-4105-8a29-c76cd022586a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRoyalties_07b255e5-a596-4517-a5a1-6f80f7573aa2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForRoyalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_09c5a85c-76a3-4c54-8bde-5df28173f24f" xlink:to="loc_us-gaap_PaymentsForRoyalties_07b255e5-a596-4517-a5a1-6f80f7573aa2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_1096d975-32b6-4ede-a4ac-04cacb6255ef" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_09c5a85c-76a3-4c54-8bde-5df28173f24f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_1096d975-32b6-4ede-a4ac-04cacb6255ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_BusinessCombinationContingentConsiderationEarnedAndAccruedInOperatingExpenses_36fc795f-d8e3-4e43-9780-62ed00f594ce" xlink:href="cpix-20250331.xsd#cpix_BusinessCombinationContingentConsiderationEarnedAndAccruedInOperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_09c5a85c-76a3-4c54-8bde-5df28173f24f" xlink:to="loc_cpix_BusinessCombinationContingentConsiderationEarnedAndAccruedInOperatingExpenses_36fc795f-d8e3-4e43-9780-62ed00f594ce" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_8faa3f90-674e-4e8f-bd22-f5d10204af37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cumberlandpharma.com/role/ProductAcquisitionsAndReturnOfProductRightsChangeinConsiderationSancusoAcquisitionDetails" xlink:type="simple" xlink:href="cpix-20250331.xsd#ProductAcquisitionsAndReturnOfProductRightsChangeinConsiderationSancusoAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://www.cumberlandpharma.com/role/ProductAcquisitionsAndReturnOfProductRightsChangeinConsiderationSancusoAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_4c3709a8-2f3f-49c4-8187-3194e7036571" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3d533ea6-e4ef-495e-8fad-fd9855be9515" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4c3709a8-2f3f-49c4-8187-3194e7036571" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3d533ea6-e4ef-495e-8fad-fd9855be9515" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d3b13c0e-f650-4da2-8323-7205636aabec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3d533ea6-e4ef-495e-8fad-fd9855be9515" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d3b13c0e-f650-4da2-8323-7205636aabec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d3b13c0e-f650-4da2-8323-7205636aabec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d3b13c0e-f650-4da2-8323-7205636aabec" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d3b13c0e-f650-4da2-8323-7205636aabec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d17f5855-0148-4e13-975f-ba8b23197c2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d3b13c0e-f650-4da2-8323-7205636aabec" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d17f5855-0148-4e13-975f-ba8b23197c2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_U.S.ProductAssetRightsSancusoMember_d7013368-e04d-4b99-ba57-80866993ac43" xlink:href="cpix-20250331.xsd#cpix_U.S.ProductAssetRightsSancusoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d17f5855-0148-4e13-975f-ba8b23197c2a" xlink:to="loc_cpix_U.S.ProductAssetRightsSancusoMember_d7013368-e04d-4b99-ba57-80866993ac43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualRollForward_911b6f82-3043-4603-b78b-741ca4c22a1e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyAccrualRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4c3709a8-2f3f-49c4-8187-3194e7036571" xlink:to="loc_us-gaap_LossContingencyAccrualRollForward_911b6f82-3043-4603-b78b-741ca4c22a1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_112f0f07-a8b0-4b51-b3a7-784b8949e3ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_911b6f82-3043-4603-b78b-741ca4c22a1e" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_112f0f07-a8b0-4b51-b3a7-784b8949e3ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRoyalties_00b15609-b665-4723-abd7-789b277ca86a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForRoyalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_911b6f82-3043-4603-b78b-741ca4c22a1e" xlink:to="loc_us-gaap_PaymentsForRoyalties_00b15609-b665-4723-abd7-789b277ca86a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_3313fdcf-9432-4eff-b863-ba3eb4e418a0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_911b6f82-3043-4603-b78b-741ca4c22a1e" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_3313fdcf-9432-4eff-b863-ba3eb4e418a0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_BusinessCombinationContingentConsiderationEarnedAndAccruedInOperatingExpenses_93b4b3c2-f04b-47dc-a459-af20059e0685" xlink:href="cpix-20250331.xsd#cpix_BusinessCombinationContingentConsiderationEarnedAndAccruedInOperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_911b6f82-3043-4603-b78b-741ca4c22a1e" xlink:to="loc_cpix_BusinessCombinationContingentConsiderationEarnedAndAccruedInOperatingExpenses_93b4b3c2-f04b-47dc-a459-af20059e0685" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_9e591898-9a2d-4d75-a44e-2ac3901cb216" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_KennethJ.KrogulskiMember_c7c6b046-9ec4-4aa9-a0a4-b73ab8987207" xlink:href="cpix-20250331.xsd#cpix_KennethJ.KrogulskiMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_cpix_KennethJ.KrogulskiMember_c7c6b046-9ec4-4aa9-a0a4-b73ab8987207" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_JamieR.JonesMember_56243329-cb44-4ad6-b6cd-b1f8f710d606" xlink:href="cpix-20250331.xsd#cpix_JamieR.JonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_cpix_JamieR.JonesMember_56243329-cb44-4ad6-b6cd-b1f8f710d606" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_CarolineR.YoungMember_e4ac180b-ba72-4f60-b211-970424cbd920" xlink:href="cpix-20250331.xsd#cpix_CarolineR.YoungMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_cpix_CarolineR.YoungMember_e4ac180b-ba72-4f60-b211-970424cbd920" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cpix_A.J.KazimiMember_2291fdd3-d4bb-4886-8f35-6817471cc73b" xlink:href="cpix-20250331.xsd#cpix_A.J.KazimiMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_cpix_A.J.KazimiMember_2291fdd3-d4bb-4886-8f35-6817471cc73b" xlink:type="arc" order="5"/>
  </link:definitionLink>
</link:linkbase>
