the act or process of making a thing resistant, as in waterproof fabrics or fireproof material.
any chemical used in the manufacture of a substance to make it proof against water, fire, etc.

Origin of proofing

First recorded in 1900–05; proof + -ing1




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 formsre-proof, verb (used with object)un·proofed, adjective

Synonyms for proof

Synonym study

1. See evidence. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for proofing

Historical Examples of proofing

  • Raw rubber has been used to some extent for proofing purposes, as for the manufacture of material for hoods of motor-cars.

  • When drawings are to be washed out for proofing or printing, the plate should first be thinly gummed up.

    Practical Lithography

    Alfred Seymour

  • The proofing machines won't operate here either, of course, and so we need human personnel.

    Helpfully Yours

    Evelyn E. Smith

  • There are, or ought to be, three aims in the process of proofing and stiffening, all the three being of equal importance.

  • Kerned types are a source of trouble because of the ease with which these projections break off during composition, proofing, etc.


    A. A. Stewart

British Dictionary definitions for proofing



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 propositionSee also direct (def. 17), induction (def. 4), induction (def. 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 impenetrabilityproof armour


(tr) 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 for proof

C13: from Old French preuve a test, from Late Latin proba, from Latin probāre to test
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

Word Origin and History for proofing



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

Science definitions for proofing



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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.