Source : Webster's Revised Unabridged Dictionary (1913)

Attest \At"test"\, v. t. [imp. & p. p. {Attested}; p. pr. & vb.
   n. {Attesting}.] [L. attestari; ad + testari to bear witness:
   cf. F. attester.]
   1. To bear witness to; to certify; to affirm to be true or
      genuine; as, to attest the truth of a writing, a copy of
      record.

            Facts . . . attested by particular pagan authors.
                                                  --Addison.

   2. To give proof of; to manifest; as, the ruins of Palmyra
      attest its ancient magnificence.

   3. To call to witness; to invoke. [Archaic]

            The sacred streams which Heaven's imperial state
            Attests in oaths, and fears to violate. --Dryden.

Attest \At*test"\, n.
   Witness; testimony; attestation. [R.]

         The attest of eyes and ears.             --Shak.

Source : WordNet®

attest
     v 1: provide evidence for; stand as proof of; show by one's
          behavior, attitude, or external attributes; "His high
          fever attested to his illness"; "The buildings in Rome
          manifest a high level of architectural sophistication";
          "This decision demonstrates his sense of fairness" [syn:
           {certify}, {manifest}, {demonstrate}, {evidence}]
     2: authenticate, affirm to be true, genuine, or correct, as in
        an official capacity; "I attest this signature"
     3: give testimony in a court of law [syn: {testify}, {take the
        stand}, {bear witness}]
     4: establish or verify the usage of; "This word is not attested
        until 1993"