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