\ ˈprüf How to pronounce proof (audio) \

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 combinationwindproof
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
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

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.
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Recent Examples on the Web: Noun The plot revolves around a corporate lawyer from humble roots who finds himself in possession of damning proof linking unexplained deaths in West Virginia to the chemical giant DuPont. Willie Brown,, "Big names, bigger show give 2019 a grand exit in North Beach," 4 Jan. 2020 The icky act sparked the #IceCreamChallenge, in which others also licked unsold ice cream and posted video proof on social media. Amir Vera, CNN, "From licking ice cream to storming Area 51, these 8 stories made 2019 a wild year," 29 Dec. 2019 The rocket has offered definitive proof that a private company can, independently, build a heavy-lift rocket without direct government oversight. Eric Berger, Ars Technica, "After an amazing decade in space, these are humanity’s top achievements," 27 Dec. 2019 Nor does the law require proof that the disseminator of the images intended to cause harm, the court noted. Arluther Lee, ajc, "Court: Revenge porn conviction violated man’s free speech rights," 24 Dec. 2019 Critics, like civil rights attorney Sarah Gelsolimo, said the county has not demonstrated hard proof that conditions at the jail have substantially changed. Adam Ferrise, cleveland, "One year later, Cuyahoga County Jail makes slew of changes after string of inmate deaths," 23 Dec. 2019 Trump, the official said, offered no proof to support his theory of Ukraine's involvement. Anchorage Daily News, "Former White House officials say they feared Putin influenced the president’s views on Ukraine, 2016 campaign," 20 Dec. 2019 The impressive demo might seem like further evidence of China’s AI prowess—perhaps even proof that the country is poised to eclipse the US in this critical area. Will Knight, Wired, "China's AI Unicorns Can Spot Faces. Now They Need New Tricks," 12 Dec. 2019 New York’s Metropolitan Transportation Authority has used several contractors to flood-proof its systems, and mentions climate change in a recent announcement about closing the Coney Island Yard for upgrades. Kimberly Miller,, "This Palm Beach County business is front and center in fighting flooding," 5 Dec. 2019 Recent Examples on the Web: Adjective Lightly butter a baking dish, pie plate, or oven-proof pan. Eric Velasco, al, "How to make crepes at home," 26 Dec. 2019 The minerals mined in Alaska can turn up in some surprising places as well -- like your car, where the sensor that triggers your airbag is made of rust-proof gold. Anchorage Daily News, "Where do Alaska’s metals end up? Check your pocket.," 19 Dec. 2019 In the chamber with a veto-proof Democratic majority, all the leadership positions are held by Democrats and legislation is vetted by four main committees. Erin Cox, Washington Post, "New leaders in Maryland Senate will be younger, more left-leaning," 12 Dec. 2019 The ordinance requires owners of alligators, crocodiles and venomous snakes to store and transport their pets in escape-proof containers. USA TODAY, "First Spouse Dolls, Snowstang, sand sculpture: News from around our 50 states," 7 Dec. 2019 Advances in technology mean that travelers can now purchase a cashmere sweater that doubles as a water- and wind-proof jacket. Louis Cheslaw, Condé Nast Traveler, "13 Gifts for the Business Class Regular," 6 Dec. 2019 The high burden-of-proof threshold and the reluctance of cops to testify against their own in such cases were cited as factors in the high no-charge rate. Rubén Rosario, Twin Cities, "Rosario: For Frank Baker, cop verdict brings a measure of justice," 1 Dec. 2019 Indigenous peoples in what is today South America were brushing rubber-tree sap, or natural rubber latex, to make items such as rain-proof capes long before Europeans reached their shores. Marc Bain, Quartzy, "The North Face’s new fabric is the latest attempt in an endless struggle to stay dry," 31 Oct. 2019 Unlike other waterproof mascaras, the flake-proof formula won’t require a heavy-duty makeup remover or painful tugging to take off. Braelyn Wood,, "Blinc Mascara Is The Best Waterproof Mascara You Can Buy To Avoid Flaking and Smudging," 30 Oct. 2019 Recent Examples on the Web: Verb Also, some recipes call for proofing dough in a warm place, like on top of the refrigerator. oregonlive, "Why didn’t my bread rise? 8 common baking mistakes that can cause homemade loaves to fall flat," 27 Dec. 2019 Think of these as seasonal chores like winter-proofing your house, or take the anthropologist-from-Mars perspective to keep yourself amused., "Need advice? Submit questions for Miss Conduct here.," 22 Nov. 2019 Wi-Fi 6 is a very new standard, but its spec has been finalized, so there’s little risk in Apple future-proofing with this even though most consumers don’t have any other Wi-Fi 6 hardware yet. Samuel Axon, Ars Technica, "iPhone 11 Pro and 11 Pro Max review: High quality for high prices," 26 Sep. 2019 School officials are working on repairs and flood proofing the building, which is expected to be completed by January 2020. Savannah Mehrtens, Houston Chronicle, "Repetitive flooding at St. Martha leaves school leaders seeking solutions," 9 Dec. 2019 Virginia estimates that the relocation and flood-proofing projects, started almost 20 years ago, cost $170 million in federal and state funds, more than $170,000 for every woman, man and child living in town today. Eduardo Porter, New York Times, "Can a Coal Town Reinvent Itself?," 6 Dec. 2019 In the lineup is South Holland where a home flood-proofing program is gaining results. Lisa Donovan,, "The Spin: Illinois officially enters 2020 election season; Elizabeth Warren heading to Chicago for town hall this weekend," 25 Nov. 2019 That's great news for existing and future Quest owners, in terms of future-proofing its device to some extent. Sam Machkovech, Ars Technica, "We put Oculus Quest’s two craziest new VR features through their paces," 27 Sep. 2019 The effort to make more permanent safeguards, like undergrounding lines and fire-proofing poles, is expected to take decades. Megan Cassidy,, "California’s new challenge: responding to blazes like Kincade Fire during power outages," 24 Oct. 2019

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

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Time Traveler for proof

Time Traveler

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

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Statistics for proof

Last Updated

8 Jan 2020

Cite this Entry

“Proof.” The Dictionary, Merriam-Webster Inc., Accessed 17 January 2020.

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More Definitions for proof


How to pronounce proof (audio)

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)

formal : designed or made to prevent or protect against something harmful


\ ˈprüf How to pronounce proof (audio) \

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

History and Etymology for proof

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

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More from Merriam-Webster on proof

Thesaurus: All synonyms and antonyms for proof

Rhyming Dictionary: Words that rhyme with proof

Spanish Central: Translation of proof

Nglish: Translation of proof for Spanish Speakers

Britannica English: Translation of proof for Arabic Speakers Encyclopedia article about proof

Comments on proof

What made you want to look up proof? Please tell us where you read or heard it (including the quote, if possible).


a plan in which a last survivor takes all

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