authenticate

1 to declare (something) to be true or genuine a jeweler authenticated the diamond as real Synonyms attest, certify, avouch, testify (to), vouch (for), witnessRelated Words guarantee, warrant; affirm, assert, aver, avow, profess, vow

2 to give evidence or testimony to the truth or factualness of we require more than simply your word to authenticate this story Synonyms argue, attest, confirm, bear out, certify, corroborate, substantiate, support, validate, verify, vindicateRelated Words avouch, back (up), testify (to), vouch (for), witness; guarantee, warrant; affirm, assert, aver, avow, declare, profess; demonstrate, document, establish, prove, reinforce (also reenforce)Near Antonyms contradict, gainsay; deny, disavow, disclaim; challenge, contest, dispute, questionAntonyms disprove, rebut, refute