Source : Webster's Revised Unabridged Dictionary (1913)

Proof \Proof\, n. [OF. prove, proeve, F. preuve, fr. L. proba,
   fr. probare to prove. See {Prove}.]
   1. Any effort, process, or operation designed to establish or
      discover a fact or truth; an act of testing; a test; a
      trial.

            For whatsoever mother wit or art Could work, he put
            in proof.                             --Spenser.

            You shall have many proofs to show your skill.
                                                  --Ford.

            Formerly, a very rude mode of ascertaining the
            strength of spirits was practiced, called the proof.
                                                  --Ure.

   2. That degree of evidence which convinces the mind of any
      truth or fact, and produces belief; a test by facts or
      arguments that induce, or tend to induce, certainty of the
      judgment; conclusive evidence; demonstration.

            I'll have some proof.                 --Shak.

            It is no proof of a man's understanding to be able
            to confirm whatever he pleases.       --Emerson.

   Note: Properly speaking, proof is the effect or result of
         evidence, evidence is the medium of proof. Cf.
         {Demonstration}, 1.

   3. The quality or state of having been proved or tried;
      firmness or hardness that resists impression, or does not
      yield to force; impenetrability of physical bodies.

   4. Firmness of mind; stability not to be shaken.

   5. (Print.) A trial impression, as from type, taken for
      correction or examination; -- called also {proof sheet}.

   6. (Math.) A process for testing the accuracy of an operation
      performed. Cf. {Prove}, v. t., 5.

   7. Armor of excellent or tried quality, and deemed
      impenetrable; properly, armor of proof. [Obs.] --Shak.

   {Artist's proof}, a very early proof impression of an
      engraving, or the like; -- often distinguished by the
      artist's signature.

   {Proof reader}, one who reads, and marks correction in,
      proofs. See def. 5, above.

   Syn: Testimony; evidence; reason; argument; trial;
        demonstration. See {Testimony}.