attest

1 to declare (something) to be true or genuine <the appraiser attests that the lamp is indeed an original Tiffany> Synonyms certify, authenticate, avouch, testify (to), vouch (for), witnessRelated Words guarantee, warrant; affirm, assert, aver, avow, profess, vow

2 to make a solemn declaration under oath for the purpose of establishing a fact <an eyewitness who will attest to my innocence> Synonyms testify, depose, swear, witnessRelated Words verify; vouch; promise, vow

3 to give evidence or testimony to the truth or factualness of <I'll attest that she was at the party> Synonyms argue, confirm, authenticate, 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