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

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2022 Workiva-->
<!--r:8c03f7b9-cb30-4c62-a9d3-1b9ac715cbc9,g:2a088d60-a913-4073-956b-47598951a135-->
<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://cumberlandpharma.com/role/DocumentandEntityInformationDocument" xlink:type="simple" xlink:href="cpix-20220322.xsd#DocumentandEntityInformationDocument"/>
  <link:definitionLink xlink:role="http://cumberlandpharma.com/role/DocumentandEntityInformationDocument" xlink:type="extended" id="ie9274bff6dfa425ca2f9243ec87b2de7_DocumentandEntityInformationDocument">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_ed9b1bb4-af28-4436-8575-2767f72047b6" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_DocumentType_ed9b1bb4-af28-4436-8575-2767f72047b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_ee12c32d-e4bf-4ca7-8706-b88eb9e6f070" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_DocumentPeriodEndDate_ee12c32d-e4bf-4ca7-8706-b88eb9e6f070" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_78e27c7c-8b1c-4dba-9978-7934b26b30b4" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityRegistrantName_78e27c7c-8b1c-4dba-9978-7934b26b30b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_8e617fa0-a113-4e98-89f4-862b0b55bc08" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityCentralIndexKey_8e617fa0-a113-4e98-89f4-862b0b55bc08" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_316f487d-db01-4f20-a137-f8515ff3e4cf" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_AmendmentFlag_316f487d-db01-4f20-a137-f8515ff3e4cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_e179a156-1987-4636-b1b3-41fc9612d1b4" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityIncorporationStateCountryCode_e179a156-1987-4636-b1b3-41fc9612d1b4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_0c003f38-6a45-45da-8a9d-c27e07893fe2" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityFileNumber_0c003f38-6a45-45da-8a9d-c27e07893fe2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_7544ee80-e616-475b-9ee7-9e533509d76e" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityTaxIdentificationNumber_7544ee80-e616-475b-9ee7-9e533509d76e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_43a32b7a-3625-452a-b9c4-9bf291f9a192" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_CityAreaCode_43a32b7a-3625-452a-b9c4-9bf291f9a192" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_cc2ca834-a566-47f5-81f6-2ed12248a705" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_LocalPhoneNumber_cc2ca834-a566-47f5-81f6-2ed12248a705" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_144744e4-16da-4d87-b343-c2e37dd070dc" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_WrittenCommunications_144744e4-16da-4d87-b343-c2e37dd070dc" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_8290077d-f9c5-400a-951d-db695795b326" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_SolicitingMaterial_8290077d-f9c5-400a-951d-db695795b326" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_2c922dd3-13bb-4ae0-b9fd-9064eb2a990a" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_PreCommencementTenderOffer_2c922dd3-13bb-4ae0-b9fd-9064eb2a990a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_9e5fa91b-f451-402d-9431-b71f8c5d1a15" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_9e5fa91b-f451-402d-9431-b71f8c5d1a15" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_64f4b229-f82a-4952-9a66-1306cae3a6c8" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_Security12bTitle_64f4b229-f82a-4952-9a66-1306cae3a6c8" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_0f0f33cd-e760-4452-b6e5-6683c2a9f5b4" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_TradingSymbol_0f0f33cd-e760-4452-b6e5-6683c2a9f5b4" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_72da1db4-c39f-4910-8fd7-a614de9badf2" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_SecurityExchangeName_72da1db4-c39f-4910-8fd7-a614de9badf2" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_47bf7064-03fc-4cac-9ad3-3deed6552d07" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityEmergingGrowthCompany_47bf7064-03fc-4cac-9ad3-3deed6552d07" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_ca316b83-8838-4775-a521-f327b0290e47" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityAddressAddressLine1_ca316b83-8838-4775-a521-f327b0290e47" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_2224d313-570c-4834-a8f7-f1697ed9c007" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityAddressPostalZipCode_2224d313-570c-4834-a8f7-f1697ed9c007" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_9e7d7038-d4e9-4b4e-8428-4b3396b131c1" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityAddressCityOrTown_9e7d7038-d4e9-4b4e-8428-4b3396b131c1" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_6baa427f-ad6c-4683-8d4c-bb2b21ecf61a" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntityAddressStateOrProvince_6baa427f-ad6c-4683-8d4c-bb2b21ecf61a" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_221a7841-763a-4bf1-ae70-98df3c07fe27" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_93559f92-a30d-4104-9c33-3c3954b551ef" xlink:to="loc_dei_EntitiesTable_221a7841-763a-4bf1-ae70-98df3c07fe27" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
  </link:definitionLink>
</link:linkbase>
