1. The evidence or argument that compels the mind to accept an assertion as true.
a. The validation of a proposition by application of specified rules, as of induction or deduction, to assumptions, axioms, and sequentially derived conclusions.
b. A statement or argument used in such a validation.
a. Convincing or persuasive demonstration: was asked for proof of his identity; an employment history that was proof of her dependability.
b. The state of being convinced or persuaded by consideration of evidence.
4. Determination of the quality of something by testing; trial: put one's beliefs to the proof.
a. The establishment of the truth or falsity of an allegation by evidence.
b. The evidence offered in support of or in contravention of an allegation.
6. The alcoholic strength of a liquor, expressed by a number that is twice the percentage by volume of alcohol present.
a. A trial sheet of printed material that is made to be checked and corrected. Also called proof sheet.
b. A trial impression of a plate, stone, or block taken at any of various stages in engraving.
a. A trial photographic print.
b. 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.
9. Archaic Proven impenetrability: "I was clothed in Armor of proof" (John Bunyan).
1. Fully or successfully resistant; impervious. Often used in combination: waterproof watches; a fireproof cellar door.
2. Of standard alcoholic strength: proof liquor.
3. Used to proofread or correct typeset copy: a proof copy of the manuscript.
v. proofed, proof·ing, proofs
a. To make a trial impression of (printed or engraved matter).
b. To proofread (copy).
a. To activate (dormant dry yeast) by adding water.
b. To work (dough) into proper lightness.
3. To treat so as to make resistant: proof a fabric against shrinkage.
1. Printing To proofread.
2. To become properly light for cooking: The batter proofed overnight.
[Middle English prove, preve, from Anglo-Norman prove and from Old French prueve, both from Late Latin proba, from Latin probāre, to prove; see PROVE.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.