proof

1 of 3

noun

1
a
: 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
6
a
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
8
a
: 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

2 of 3

adjective

1
: able to resist or repel
boots that were … proof against cold and wetRobertson 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

proof

3 of 3

verb

proofed; proofing; proofs

transitive verb

1
a
: to make or take a proof or test of
b
2
: to give a resistant quality to
3
: to activate (yeast) by mixing with water and sometimes sugar or milk
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.
Recent Examples on the Web
Noun
Social proof, such as reviews, testimonials, and case studies, can be a powerful tool to build trust with potential customers. Abdo Riani, Forbes, 19 Oct. 2024 Our spring 2025 street style photos are proof that a good pair of shoes really can take you places. Irene Kim, Vogue, 19 Oct. 2024
Adjective
The goal is to reach Stage 2, where proof systems become fully trustless and security councils intervene only for provable bugs. Andrey Sergeenkov, Forbes, 17 Oct. 2024 Tao: Technically they aren’t classified as AI, but proof assistants are useful computer tools that check whether a mathematical argument is correct or not. Matteo Wong, The Atlantic, 4 Oct. 2024
Verb
By encouraging and enabling others to grow, take risks and fuel innovation, business leaders are not only driving greater engagement and performance, but also future proofing their organization for years to come. Fortune Editors, Fortune, 2 Oct. 2024 By encouraging and enabling others to grow, take risks, and fuel innovation, business leaders are not only driving greater engagement in performance, but also future proofing their organization for years to come. Fortune Editors, Fortune, 19 Sep. 2024 See all Example Sentences for proof 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'proof.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Noun

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

First Known Use

Noun

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

Adjective

1583, in the meaning defined at sense 1

Verb

circa 1699, in the meaning defined at sense 1a

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

Dictionary Entries Near proof

Cite this Entry

“Proof.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proof. Accessed 31 Oct. 2024.

Kids Definition

proof

1 of 3 noun
1
a
: evidence of truth or correctness
gave proof of her statement
b
: an act or process of showing or finding out that something is true especially by reasoning or by experiment
a proof that the theorem is true
put a theory to the proof
2
a
: a copy (as of something set in type) taken for study and correction
b
: a test print made from a photographic negative

proof

2 of 3 adjective
: designed or made to prevent or keep out something that could be harmful
this lock is proof against tampering
often used in compounds
waterproof

proof

3 of 3 verb
: to activate (yeast) by mixing with water

Legal Definition

proof

noun
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
4
Etymology

Noun

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

More from Merriam-Webster on proof

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