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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019dd9b2-d47d-7e4d-8a9e-d366f270b401,g:04dbf4a0-8cbe-4e78-9b73-820876b0b622-->
<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://xbrl.sec.gov/oef/role/SeriesOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#SeriesOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/oef/role/SeriesOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0000898745_S000007077Member_019dd9b2-d47d-7498-a38a-394276dbdd17" xlink:href="ck0000898745-20260615.xsd#ck0000898745_S000007077Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain" xlink:to="loc_ck0000898745_S000007077Member_019dd9b2-d47d-7498-a38a-394276dbdd17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0000898745_S000007122Member_019e6f2a-9eb1-776f-8955-c65ee7878abd" xlink:href="ck0000898745-20260615.xsd#ck0000898745_S000007122Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain" xlink:to="loc_ck0000898745_S000007122Member_019e6f2a-9eb1-776f-8955-c65ee7878abd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0000898745_S000014237Member_019e6f2c-91ca-754d-9f74-2b1d5ef37c42" xlink:href="ck0000898745-20260615.xsd#ck0000898745_S000014237Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain" xlink:to="loc_ck0000898745_S000014237Member_019e6f2c-91ca-754d-9f74-2b1d5ef37c42" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/rr/role/RiskOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#RiskOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/rr/role/RiskOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_oef_AllRisksMember" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_AllRisksMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0000898745_AlternativeMinimumTaxRiskMember_019e6f2e-e935-7085-ae2e-98f28e79a4fb" xlink:href="ck0000898745-20260615.xsd#ck0000898745_AlternativeMinimumTaxRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0000898745_AlternativeMinimumTaxRiskMember_019e6f2e-e935-7085-ae2e-98f28e79a4fb" xlink:type="arc" order="9"/>
  </link:definitionLink>
</link:linkbase>
