authenticate(v = verb.cognition) - establish the authenticity of something;
is one way to attest, certify, demonstrate, evidence, manifest
Derived forms noun authentication₂, noun authentication₁, noun authenticator₁
Sample sentences: Somebody ----s something; Something ----s something

1.  To render authentic; to give authority to, by the proof, attestation, or formalities required by law, or sufficient to entitle to credit. [1913 Webster]
"The king serves only as a notary to authenticate the choice of judges." [1913 Webster]

2.  To prove authentic; to determine as real and true; as, to authenticate a portrait. Walpole. [1913 Webster]

authenticate, v.tr.
1 establish the truth or genuineness of.
2 validate.

Derivative:
authentication n. authenticator n.

Etymology:
med.L authenticare f. LL authenticus: see AUTHENTIC

VB  be evidence, evince, show, betoken, tell of, indicate, imply, involve, argue, bespeak, breathe, have weight, carry weight, tell, speak volumes, speak for itself, rest upon, depend upon, repose on, bear witness, give evidence, testify, depose, witness, vouch for, sign, seal, undersign, set one's hand and seal, sign and seal, deliver as one's act and deed, certify, attest, acknowledge, make absolute, confirm, prove (demonstrate), indorse, countersign, corroborate, support, ratify, bear out, uphold, warrant, adduce, attest, cite, quote, refer to, appeal to, call, call to witness, bring forward, bring into court, allege, plead, produce witnesses, confront witnesses, place into evidence, mark into evidence, collect evidence, bring together evidence, rake up evidence, experiment, have a case, make out a case, establish, authenticate, substantiate, verify, make good, quote chapter and verse, bring home to, bring to book.