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[proof] /pruf/
evidence sufficient to establish a thing as true, or to produce belief in its truth.
anything serving as such evidence:
What proof do you have?
the act of testing or making trial of anything; test; trial:
to put a thing to the proof.
the establishment of the truth of anything; demonstration.
Law. (in judicial proceedings) evidence having probative weight.
the effect of evidence in convincing the mind.
an arithmetical operation serving to check the correctness of a calculation.
Mathematics, Logic. a sequence of steps, statements, or demonstrations that leads to a valid conclusion.
a test to determine the quality, durability, etc., of materials used in manufacture.
  1. the arbitrary standard strength, as of an alcoholic liquor.
  2. strength with reference to this standard: “100 proof” signifies a proof spirit, usually 50% alcohol.
Photography. a trial print from a negative.
  1. a trial impression, as of composed type, taken to correct errors and make alterations.
  2. one of a number of early and superior impressions taken before the printing of the ordinary issue:
    to pull a proof.
(in printmaking) an impression taken from a plate or the like to show the quality or condition of work during the process of execution; a print pulled for examination while working on a plate, block, stone, etc.
Numismatics. one of a limited number of coins of a new issue struck from polished dies on a blank having a polished or matte surface.
the state of having been tested and approved.
proved strength, as of armor.
Scots Law. the trial of a case by a judge alone, without a jury.
able to withstand; successful in not being overcome:
proof against temptation.
impenetrable, impervious, or invulnerable:
proof against outside temperature changes.
used for testing or proving; serving as proof.
of standard strength, as an alcoholic liquor.
of tested or proven strength or quality:
proof armor.
noting pieces of pure gold and silver that the U.S. assay and mint offices use as standards.
verb (used with object)
to test; examine for flaws, errors, etc.; check against a standard or standards.
Printing. prove (def 7).
to proofread.
to treat or coat for the purpose of rendering resistant to deterioration, damage, etc. (often used in combination):
to proof a house against termites; to shrink-proof a shirt.
  1. to test the effectiveness of (yeast), as by combining with warm water so that a bubbling action occurs.
  2. to cause (especially bread dough) to rise due to the addition of baker's yeast or other leavening.
Origin of proof
1175-1225; Middle English prove, prooff, prof, proufe, alteration (by association with the vowel of prove) of preove, proeve, prieve, pref < Middle French preve, proeve, prueve < Late Latin proba a test, akin to Latin probāre to test and find good; cf. pree
Related forms
re-proof, verb (used with object)
unproofed, adjective
1. confirmation, demonstration, corroboration, support. See evidence. 3. examination, assay. 18. firm, steadfast.


a combining form meaning “resistant, impervious to” that specified by the initial element:
burglarproof; childproof; waterproof. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for proof
Contemporary Examples
Historical Examples
  • Not only that, but they are a proof that environment can move a man when free will fails.

    Not Guilty Robert Blatchford
  • And this brings me to something which I think ought to be said, though I have no proof to bring.

    Deerbrook Harriet Martineau
  • Pray, sir, what proof can you bring of your insulting accusations?

    Mildred's New Daughter Martha Finley
  • "Graft" is only a proof of the wide extent to which this lesson to get into the steal is learned.

    Folkways William Graham Sumner
  • Giles had refused to believe his assertion of innocence, and he had no proof.

    Uncle Max Rosa Nouchette Carey
British Dictionary definitions for proof


any evidence that establishes or helps to establish the truth, validity, quality, etc, of something
(law) the whole body of evidence upon which the verdict of a court is based
(maths, logic) a sequence of steps or statements that establishes the truth of a proposition See also direct (sense 17), induction (sense 4), induction (sense 8)
the act of testing the truth of something (esp in the phrase put to the proof)
(Scots law) trial before a judge without a jury
(printing) a trial impression made from composed type, or a print-out (from a laser printer, etc) for the correction of errors
(in engraving, etc) a print made by an artist or under his supervision for his own satisfaction before he hands the plate over to a professional printer
(photog) a trial print from a negative
  1. the alcoholic strength of proof spirit
  2. the strength of a beverage or other alcoholic liquor as measured on a scale in which the strength of proof spirit is 100 degrees
(usually postpositive) foll by against. able to resist; impervious (to): the roof is proof against rain
having the alcoholic strength of proof spirit
of proved strength or impenetrability: proof armour
(transitive) to take a proof from (type matter, a plate, etc)
to proofread (text) or inspect (a print, etc), as for approval
to render (something) proof, esp to waterproof
Word Origin
C13: from Old French preuve a test, from Late Latin proba, from Latin probāre to test


adjective, combining form
secure against (damage by); (make) impervious to: waterproof, mothproof, childproof
Word Origin
from proof (adj)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for proof

early 13c., preove "evidence to establish the fact of (something)," from Anglo-French preove, Old French prueve "proof, test, experience" (13c., Modern French preuve), from Late Latin proba "a proof," a back-formation from Latin probare "to prove" (see prove). "The devocalization of v to f ensued upon the loss of final e; cf. the relation of v and f in believe, belief, relieve, relief, behove, behoof, etc. [OED].

Meaning "act of proving" is early 14c. Meaning "act of testing or making trial of anything" is from late 14c., from influence of prove. Meaning "standard of strength of distilled liquor" is from 1705. In photography from 1855. Typographical sense of "trial impression to test type" is from c.1600. Numismatic sense of "coin struck to test a die" is from 1762; now mostly in reference to coins struck from highly polished dies, mainly for collectors.

Adjectival sense (proof against) is recorded from 1590s, from the noun in expressions such as proof of (mid-15c.), hence extended senses involving "tested power" in compounds such as fireproof (1630s), waterproof (1725), foolproof (1902), etc. Shakespeare has shame-proof.


1834, "to test," from proof (n.). From 1950 as short for proofread (v.). Related: Proofed; proofing.

Online Etymology Dictionary, © 2010 Douglas Harper
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proof in Science
A demonstration of the truth of a mathematical or logical statement, based on axioms and theorems derived from those axioms.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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proof in Technology

1. A finite sequence of well-formed formulas, F1, F2, ... Fn, where each Fi either is an axiom, or follows by some rule of inference from some of the previous F's, and Fn is the statement being proved.
See also proof theory.
2. A left-associative natural language parser by Craig R. Latta . Ported to Decstation 3100, Sun-4.
E-mail: . Mailing list: (Subject: add me).
The Free On-line Dictionary of Computing, © Denis Howe 2010
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