proof

noun

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\ 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

proof

adjective

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 combinationwindproof

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

3 : of standard strength or quality or alcoholic content

proof

verb

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

Other Words from proof Synonyms & Antonyms More Example Sentences Learn More about proof

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Examples of proof in a Sentence

Noun 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. Verb She proofed the story carefully.

Recent Examples on the Web: Noun The United States now requires travelers to provide proof of a negative coronavirus test before flying from the U.K., but the rule didn’t take effect until Monday. — Alex Wigglesworth, Los Angeles Times, "New, possibly more contagious coronavirus strain detected in Big Bear," 2 Jan. 2021 Before boarding, each guest—limited to residents of Germany, Austria, and Switzerland—had to provide proof of a negative COVID-19 test. — Davide Bertuccio, Travel, "Why cruise ships are setting sail again as COVID-19 rages," 25 Dec. 2020 In some of the previous loses, judges criticized Republicans for making sweeping allegations of voting irregularities and fraud without any proof. — Brent Kendall And Deanna Paul, WSJ, "Trump’s Challenges to Election Results Face End of the Legal Road," 10 Dec. 2020 The president has even suggested without proof that Pfizer intentionally withheld clinical trial data showing its success until after the election to undercut his chances at a second term. — David Jackson, USA TODAY, "President Trump to hold White House COVID-19 summit as pressure mounts for FDA vaccine approval," 7 Dec. 2020 After gathering statements from both parties, police told the victim that without proof of the threat, the suspect could not be charged with a crime. — Brian Lisik, cleveland, "Man accuses woman of threatening him with gun: Brunswick Hills Township Police Blotter," 7 Dec. 2020 Trump’s campaign has already failed elsewhere in court without proof of widespread fraud, which experts widely agree doesn’t exist. — Arkansas Online, "Completed Wisconsin recount confirms Biden's win over Trump," 29 Nov. 2020 If for some reason a traveler shows up to the state without proof of a negative test, they’ll be required to quarantine for 14 days, or until the end of their travel to the state. — Annie Berman, Anchorage Daily News, "Alaska health officials are recommending against travel this holiday season. Here’s what you need to know if you must go.," 23 Nov. 2020 Trump's campaign has failed to make any real headway in court without proof of widespread fraud, which experts widely agree doesn't exist. — Star Tribune, "EXPLAINER: Trump's election challenges falling flat in court," 21 Nov. 2020 Recent Examples on the Web: Adjective What 2020 taught us is that even the most recession-proof jobs can be challenged in some circumstances. — Washington Post, "Investing in 2020 was a scary, bumpy ride. Here’s what to expect in 2021.," 29 Dec. 2020 Senior lawmakers shepherding the legislation had hoped that mustering a veto-proof majority in favor of it would cow Mr. Trump into signing the bill. — New York Times, "House Votes to Override Trump’s Veto of Military Bill," 28 Dec. 2020 Christian had a handgun, bullet-proof vest, ammunition and evidence of identity theft at his Hallandale Beach home. — Wayne K. Roustan, sun-sentinel.com, "Four arrested, guns and drugs seized in probation sweep in Broward County," 19 Dec. 2020 The House approved final passage by a veto-proof 335-78 majority. — Jack Hagel And Ian Talley, WSJ, "Congress Approves Anti-Money-Laundering Measure," 11 Dec. 2020 This evolutionary masterpiece has an even greater trick -- its scales, which researchers have compared to a bullet-proof vest, protect it from piranha attacks. — Tom Page, CNN, "How Amazonians saved a 'Terminator' of the fish world," 17 Nov. 2020 Temperature checks were not a fool-proof way of detecting anyone carrying the virus. — Rob Crilly, Washington Examiner, "White House drops temperature checks for those entering complex," 22 June 2020 During the artistic checkup, conservators will briefly remove the portrait from its bullet-proof glass display case and assess its condition. — Isis Davis-marks, Smithsonian Magazine, "How You Could Be One of the Only People in the Room With the ‘Mona Lisa’," 2 Dec. 2020 Democrats hold super majorities in the Senate and House but did not secure a walkout-proof majority in this month’s election. — oregonlive, "Senate Democrats name leaders for 2021 legislative session," 15 Nov. 2020 Recent Examples on the Web: Verb Were the disappearing monoliths proof that nothing, not even 2020, lasts forever? — oregonlive, "The bird vote, Mr. Peanut’s shock sacrifice, Spike Lee’s Viagra: 10 of the strangest stories of 2020," 27 Dec. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020 Is this stunt merely proof that the chain can so successfully mimic chicken-like properties that its new sandwich must taste convincingly like the genuine article? — Author: Emily Heil, Anchorage Daily News, "Bacon- and chicken-scented masks are here and, really, you shouldn’t be surprised," 20 Oct. 2020

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.