| Authenticate 1. (v. t.) To render authentic; to give authority to, by the proof, attestation, or formalities required by law, or sufficient to entitle to credit. 2. (v. t.) To prove authentic; to determine as real and true; as, to authenticate a portrait. Thesaurus Entries OK, accept, accredit, affirm, amen, approve, attest, authorize, autograph, avouch, back, back up, bear out, bolster, buttress, certify, circumstantiate, confirm, corroborate, cosign, countersign, demonstrate, document, endorse, fortify, give permission, give the go-ahead, give the imprimatur, give thumbs up, initial, justify, notarize, pass, pass on, pass upon, permit, probate, prove, ratify, reinforce, rubber stamp, sanction, say amen to, seal, second, sign, sign and seal, strengthen, subscribe to, substantiate, support, sustain, swear and affirm, swear to, test, try, undergird, undersign, underwrite, uphold, validate, verify, visa, vise, vouch for, warrant |