The evidence or argument that compels the mind to accept an assertion as true. The validation of a proposition by application of specified rules, as of induction or deduction, to assumptions, axioms, and sequentially derived conclusions. A statement or argument used in such a validation. Convincing or persuasive demonstration: was asked for proof of his identity; an employment history that was proof of her dependability. The state of being convinced or persuaded by consideration of evidence. Determination of the quality of something by testing; trial: put one's beliefs to the proof. Law The result or effect of evidence; the establishment or denial of a fact by evidence. The alcoholic strength of a liquor, expressed by a number that is twice the percentage by volume of alcohol present. Printing A trial sheet of printed material that is made to be checked and corrected. Also called proof sheet. Printing A trial impression of a plate, stone, or block taken at any of various stages in engraving. A trial photographic print. Any of a limited number of newly minted coins or medals struck as specimens and for collectors from a new die on a polished planchet. Archaic Proven impenetrability: "I was clothed in Armor of proof\u201d ( John Bunyan). Fully or successfully resistant; impervious. Often used in combination: waterproof watches; a fireproof cellar door. Of standard alcoholic strength. Used in proving or making corrections. Printing To make a trial impression of (printed or engraved matter). Printing To proofread (copy). To activate (dormant dry yeast) by adding water. To work (dough) into proper lightness. To treat so as to make resistant: proof a fabric against shrinkage. Printing To proofread. To become properly light for cooking: The batter proofed overnight.