af;firm pronunciation: function: verb etymology: middle english affermen, from anglo-french afermer, from latin affirmare, from ad- + firmare to make firm, from firmus firm — more at firmdate: 14th centurytransitive verb 1 a : validate, confirm b : to state positively lt;he affirmed his innocencegt;2 : to assert (as a judgment or decree) as valid or confirmed3 : to express dedication to lt;affirm lifegt;intransitive verb 1 : to testify or declare by affirmation as distinguished from swearing an oath2 : to uphold a judgment or decree of a lower courtsynonyms see assert— af;firm;able adjective — af;fir;mance noun