v. t. [ imp. & p. p. Authenticated p. pr. & vb. n. Authenticating (&unr_;). ] [ Cf. LL. authenticare. ] 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. Burke. [ 1913 Webster ]

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

adj. 1. established or certified as genuine.
Syn. -- attested, documented. [ WordNet 1.5 ]

n. a mark on an article of trade to indicate its origin and authenticity.
Syn. -- hallmark, assay-mark. [ WordNet 1.5 ]

2. validating the authenticity of something or someone.
Syn. -- certification. [ WordNet 1.5 ]