Synonyms of 'authenticate'

accept, accredit, affirm, amen, approve, attest, authorize, autograph, avouch, back, bear out, bolster, buttress, certify, circumstantiate, confirm, corroborate, countersign, demonstrate, document, endorse, fortify, initial, justify, notarize, pass, permit, probate, prove, ratify, reinforce, rubber stamp, sanction, seal, second, sign, strengthen, substantiate, support, sustain, test, try, undergird, underwrite, uphold, validate, verify, visa, vise, warrant