\ ˈprüf \

Definition of proof 

(Entry 1 of 3)

1a : the cogency of evidence that compels acceptance by the mind of a truth or a fact

b : the process or an instance of establishing the validity of a statement especially by derivation from other statements in accordance with principles of reasoning

2 obsolete : experience

3 : something that induces certainty or establishes validity

4 archaic : the quality or state of having been tested or tried especially : unyielding hardness

5 : evidence operating to determine the finding or judgment of a tribunal

6a plural proofs or proof : a copy (as of typeset text) made for examination or correction

b : a test impression of an engraving, etching, or lithograph

c : a coin that is struck from a highly polished die on a polished planchet, is not intended for circulation, and sometimes differs in metallic content from coins of identical design struck for circulation

d : a test photographic print made from a negative

7 : a test applied to articles or substances to determine whether they are of standard or satisfactory quality

8a : the minimum alcoholic strength of proof spirit

b : strength with reference to the standard for proof spirit specifically : alcoholic strength indicated by a number that is twice the percent by volume of alcohol present whiskey of 90 proof is 45 percent alcohol



Definition of proof (Entry 2 of 3)

1 : able to resist or repel boots that were … proof against cold and wet —Robertson Davies often used in combination windproof

2 : used in proving or testing or as a standard of comparison

3 : of standard strength or quality or alcoholic content


proofed; proofing; proofs

Definition of proof (Entry 3 of 3)

transitive verb

1a : to make or take a proof or test of

b : proofread

2 : to give a resistant quality to

3 : to activate (yeast) by mixing with water and sometimes sugar or milk

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Other words from proof


proofer noun

Examples of proof in a Sentence


The document was proof that her story was true. He claims that he was home when the murder was committed, but he has no proof. The proof shows that the theorem is true.


She proofed the story carefully.
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Recent Examples on the Web: Noun

For proof, just take a scroll through Gwen Berry’s Instagram. Jenny Mccoy, SELF, "Olympic Hammer Thrower Gwen Berry Shares Her Intense Training Regimen," 12 July 2018 People asking for his abilities, for connections, for advice, for help finding a lost pet, for proof that their loved one was okay, was still there, somewhere, thinking about them, too. Alessandra Codinha, Vogue, "Seatbelt Psychic Puts A Celebrity Medium in the Driver's Seat," 11 July 2018 Kobach countered that his office has instructed county election officials not to ask for documentary proof of citizenship from applicants, but some individuals may still present this information on their own. Roxana Hegeman, The Seattle Times, "Kansas official follows order, registers thousands to vote," 9 July 2018 And for the skeptics doubting whether the couple is actually touching, here is a close-up for proof. Erica Gonzales, Harper's BAZAAR, "Meghan Markle and Prince Harry Are Back to Holding Hands at Royal Events," 5 July 2018 Elsewhere in the country, including Florida and New York, CBP agents have recently conducted impromptu sweeps on commercial buses, asking passengers for proof of citizenship. Gaby Del Valle, Teen Vogue, "What to Do If Border Patrol Asks You for Documentation," 3 July 2018 Look no further than Kobe Bryant’s three-ring retirement tour circus for proof that L.A. is a great place for a superstar to age—gracefully or otherwise. Ben Golliver,, "LeBron Cashes Out With Lakers, Eyes Mayweather's Riches and Whole New Level of Fame," 2 July 2018 Even though plenty of people now meet long-term partners or spouses on Tinder—just peruse the New York Times wedding pages for proof—the brand’s tawdry image has stuck. Leigh Gallagher, Fortune, "Match Is the Sweetheart of Online Dating—But Can It Fend Off Facebook and Bumble?," 27 June 2018 Rewired For their proof of concept, the team started by tinkering with bits and pieces of molecules. Beth Mole, Ars Technica, "Scientists use caffeine to control genes—and treat diabetic mice with coffee," 20 June 2018

Recent Examples on the Web: Adjective

The bill did not pass the General Assembly by veto-proof margins, so more votes would have to be rounded up for an override to be successful. Chicago Tribune Staff,, "Morning Spin: Property tax reassessment measure Ald. Burke tried to block to get hearing after all," 27 Mar. 2018 The bill heads to Gov. Jay Inslee with a veto-proof margin. Washington Post, "Washington Lawmakers approve legislative records exemption," 24 Feb. 2018 Return the egg mixture to the saucepan and cook over medium heat, stirring constantly with a heat-proof spatula, until lightly thickened, 2-3 minutes (do not boil or the eggs will curdle). Debbi Snook,, "Triple Citrus Tart with Chocolate Crust and Fresh Berries (recipe)," 21 Feb. 2018 Like all seemingly fool-proof solutions, the jungle primary has produced unanticipated problems -- especially for Democrats in 2018. Chris Cillizza, CNN, "Today is the most important day of 2018 so far for Democrats' chances in the House," 5 June 2018 As for recent revelations about a search for fool-proof suffocation on the family computer, Cindy Anthony says someone else — other than Casey — was in the house. Hal Boedeker,, "'Casey Anthony's Parents Speak': Pain on display," 27 May 2018 USA Today reports that a fool-proof way of ensuring your privacy is simply not to set up the feature that allows Echo to make calls. Anna Millard,, "Amazon’s Alexa May Be Listening — But This Trick Can Stop Her," 26 May 2018 Hogan had previously been noncommittal when asked about the legislation, which passed on mostly party-line votes and by veto-proof margins in both chambers of the assembly. Scott Dance,, "Maryland Gov. Hogan will sign bill offering many community college students free tuition," 4 May 2018 The bond also includes money to complete a project the school district started in its previous bond: including bullet-proof security lobbies for all of its elementary schools. Silvia Foster-frau, San Antonio Express-News, "Northside ISD’s bond issue anticipates continuing growth," 28 Apr. 2018

Recent Examples on the Web: Verb

Check out how to get rid of as much dust in your home as possible, along with how to pollen-proof your place. Korin Miller, SELF, "What’s an Asthma Exacerbation? (Because It Sounds Really Scary.)," 11 July 2018 Never has the drama of a proofing drawer felt more alive and essential. Margaret Lyons, New York Times, "How Much Watching Time Do You Have This Weekend?," 21 June 2018 The two men proofed each other’s papers, talked about assignments, took turns at an improvised desk in the cell with a toilet seat as the chair. Nick Anderson, Washington Post, "‘Could I make it in college?’: His journey to a bachelor’s degree started behind bars," 24 May 2018 Sky would play an important role in both Disney’s and Comcast’s future-proofing efforts., "UK clears way for bidding war between Comcast and Disney over Sky," 5 June 2018 Stopping their spread is really contingent on doing other things like pollen-proofing your home or designating your room as a no-pet zone. Nina Bahadur, SELF, "How Does Allergy-Proof Bedding Actually Work?," 8 June 2018 In order for an animal to qualify, the passenger must provide a letter from a mental-health professional describing the mental or emotional disability that shows the need for the animal, and proof the professional’s licensing. Bart Jansen, USA TODAY, "American tightens leash on comfort animals flying with passengers, following Delta and United," 14 May 2018 The Senate Banking Committee voted 23 to 2 to try to stop the Trump administration from easing sanctions on ZTE without first giving Congress proof the company is following US laws. Doug Criss, CNN, "5 things for May 23: North Korea, primary results, Zuckerberg, ZTE, leukemia & germs," 23 May 2018 So now’s a good time for investors to bear-proof their 401(k)s before the next financial storm. Matthew Frankel, USA TODAY, "Ask a Fool: How much can I borrow from my retirement accounts?," 12 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'proof.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of proof


13th century, in the meaning defined at sense 1a


1583, in the meaning defined at sense 1


circa 1699, in the meaning defined at sense 1a

History and Etymology for proof


Middle English prof, prove, alteration of preve, from Anglo-French preove, from Late Latin proba, from Latin probare to prove — more at prove


alteration of Middle English preove, from Old French preuve, from Late Latin proba, from Latin probare to prove

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Statistics for proof

Last Updated

17 Sep 2018

Look-up Popularity

Time Traveler for proof

The first known use of proof was in the 13th century

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More Definitions for proof



English Language Learners Definition of proof

 (Entry 1 of 2)

: something which shows that something else is true or correct

: an act or process of showing that something is true

mathematics : a test which shows that a calculation is correct



English Language Learners Definition of proof (Entry 2 of 2)

: designed or made to prevent or protect against something harmful


\ ˈprüf \

Kids Definition of proof

 (Entry 1 of 2)

1 : evidence of truth or correctness “… Is there any clear proof … or is it mere hearsay?” —Robert Lawson, Rabbit Hill

2 : a printing (as from type) prepared for study and correction

3 : a test print made from a photographic negative

4 : test entry 1 sense 2 Let's put her theory to the proof.



Kids Definition of proof (Entry 2 of 2)

: able to keep out something that could be harmful The seal on the bottle is proof against tampering.

Hint: The adjective proof is usually used in compounds.
  • waterproof



Legal Definition of proof 

1 : the effect of evidence sufficient to persuade a reasonable person that a particular fact exists — see also evidence

2 : the establishment or persuasion by evidence that a particular fact exists — see also burden of proof

3 : something (as evidence) that proves or tends to prove the existence of a particular fact — see also clear and convincing, preponderance of the evidence, reasonable doubt, standard of proof — compare allegation, argument

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