PROOF,n.

1. Trial; essay; experiment; any effort, process or opration that ascertains truth or fact. Thus the quality of spirit is ascertained by proof; the strength of gunpowder, of firearms and of cannon is determined by proof; the correctness of operations in arithmetic is ascertained by proof.
2. In law and logic, that degree of evidence which convinces the mind of the certainty of truth or fact, and produces belief. Proof is derived from personal knowledge, or from the testimony of others, or from conclusive reasoning. Proof differs from demonstration, which is applicable only to those truths of which the contrary is inconceivable. This has neither evidence of truth, nor proof sufficient to give it warrant. – Hooker.
3. Firmness or hardness that resists impression, or yields not to force; impenetrability of physical bodies; as, a wall that is proof against shot. See arms of proof. – Dryden.
4. Firmness of mind; stability not to be shaken; as, a mind or virtue that is proof against the arts of seduction and the assaults of temptation.
5. The proof of spirits consists in little bubbles which appear on the top of the liquor after agitation, called the bead, and by the French, chapelet. Hence,
6. The degree of strength in spirit; as, high proof; first proof; second, third, or fourth proof.
7. In printing and engraving, a rough impression of a sheet, taken for correction; plur. proofs, not proves.
8. Armor sufficiently firm to resist impression. [Not used.] – Shak. Proof is used elliptically for of proof. I have found thee / Proof against all temptation. – Milton. It is sometimes followed by to, more generally by against. Proof-impression, an early impression of an engraving, considered the best as being first taken.

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. Used in proving or testing; as, a proof load, or proof charge.
3. 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.

   * Properly speaking, proof is the effect or result of evidence, evidence is the medium of proof. Cf. Demonstration, 1.

4. Firm or successful in resisting; as, proof against harm; waterproof; bombproof.
   
   

   I . . . have found thee
   Proof against all temptation. Milton.

   This was a good, stout proof article of faith. Burke.

5. 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.
6. Being of a certain standard as to strength; -- said of alcoholic liquors.
   
   

   Proof charge (Firearms), a charge of powder and ball, greater than the service charge, fired in an arm, as a gun or cannon, to test its strength. -- Proof impression. See under Impression. -- Proof load (Engin.), the greatest load than can be applied to a piece, as a beam, column, etc., without straining the piece beyond the elastic limit. -- Proof sheet. See Proof, n., 5. - - Proof spirit (Chem.), a strong distilled liquor, or mixture of alcohol and water, containing not less than a standard amount of alcohol. In the United States "proof spirit is defined by law to be that mixture of alcohol and water which contains one half of its volume of alcohol, the alcohol when at a temperature of 60° Fahrenheit being of specific gravity 0.7939 referred to water at its maximum density as unity. Proof spirit has at 60° Fahrenheit a specific gravity of 0.93353, 100 parts by volume of the same consisting of 50 parts of absolute alcohol and 53.71 parts of water," the apparent excess of water being due to contraction of the liquids on mixture. In England proof spirit is defined by Act 58, George III., to be such as shall at a temperature of 51° Fahrenheit weigh exactly the ***frac12x13] part of an equal measure of distilled water. This contains 49.3 per cent by weight, or 57.09 by volume, of alcohol. Stronger spirits, as those of about 60, 70, and 80 per cent of alcohol, are sometimes called second, third, and fourth proof spirits respectively. -- Proof staff, a straight-edge used by millers to test the flatness of a stone. -- Proof stick (Sugar Manuf.), a rod in the side of a vacuum pan, for testing the consistency of the sirup. -- Proof text, a passage of Scripture used to prove a doctrine.

7. Firmness of mind; stability not to be shaken.
8. A trial impression, as from type, taken for correction or examination; -- called also proof sheet.
9. A process for testing the accuracy of an operation performed. Cf. Prove, v. t., 5.
10. 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.