proof

noun \ ˈprüf \

|Updated on: 10 Jul 2018

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

See proof defined for English-language learners

See proof defined for kids

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.

Recent Examples of proof from the Web

After being told she would need proof that his teacher was bullying Aaron, Escotto bought a recorder, placed it in her son's backpack for four days in October and listened to 32 hours of audio.

— colleen wright, Sun-Sentinel.com, "Mom's secret recording catches kindergarten teacher calling 5-year-old a "loser"," 5 July 2018
Farmers are living proof that our soils make a difference Mike Starkey shows what’s possible on this farm in Brownsburg, Indiana.

— emily hopkins, Cincinnati.com, "Your produce is less healthy than it was 70 years ago. These farmers might change that," 4 July 2018
Still, such an advance in fertility treatments could be a critical tool for cancer patients—if the proof of concept actually holds up.

— sy mukherjee, Fortune, "Scientists Say They've Made Progress on an Artificial Ovary to Help Cancer Patients. There's a Catch," 2 July 2018
Drake is incapable of being anything other than his unadulterated, emotional self, and the lyrics on Scorpion are proof of that.

— refinery29.com, "The Most Drake Lyrics On Drake's Scorpion," 29 June 2018
Like Douglass, Lewis was himself a story; his survival was proof of a people’s vitality.

— emily bernard, The New Republic, "Zora Neale Hurston’s drive to tell the story of the slave trade’s last survivor," 19 June 2018
And the train station is proof of that — a fitting end to the long beginning of Detroit’s comeback.

— john gallagher, Detroit Free Press, "Detroit train station is city's biggest comeback moment yet," 15 June 2018
Both his standing vertical leap (33 inches) and max vertical (41 1/2 inches) were in the top 5 for all participants, and his countless put-back dunks during the season were proof of how those physical skills translate on the court.

— brendan marks, charlotteobserver, "Barely 19, Zhaire Smith has 'surprised' in NBA workouts. Could Hornets take a gamble?," 14 June 2018
But the melodic touch that cushions the blow is proof of E’s masterful dark art.

— billboard staff, Billboard, "The 50 Greatest Deep Cuts of 1998: Critics' Picks," 31 May 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.

Origin and Etymology of proof

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

NEW! Time Traveler

First Known Use: 13th century

in the meaning defined at sense 1a

See Words from the same year

proof Synonyms

Other Logic Terms

a posteriori, connotation, corollary, inference, mutually exclusive, paradox, postulate, syllogism

proof

adjective

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

See proof defined for English-language learners

Recent Examples of proof from the Web

Residents living in areas identified by FWC as bear corridors could get a bear-proof trash bin for $50.

— stephen hudak, OrlandoSentinel.com, "Apopka to consider bear ordinance, bear-resistant trash cans," 26 June 2018
For the Last Watch, high-proof Knob Creek bourbon lends a stiff Kentucky backbone to arak’s anise shade, which also takes a tart dose of lemon for a riff on whiskey sour.

— craig laban, Philly.com, "Suraya's Arak-tails showcase the Middle East's ancient anise spirit," 21 June 2018
Image As another summer approaches, low-proof drinks — both refreshing and a smart choice for long, sun-baked afternoons — are moving into wide circulation.

— jane black, New York Times, "In Summer’s Heat, Lighter Cocktails Keep You on Your Feet," 18 May 2018
The attack led officials to renew their call for residents to secure food sources and use bear-proof trash cans.

— CBS News, "911 call: Bear picked up girl "by her butt" outside her Colorado home," 15 May 2018
Place in a clean glass container and cover with high-proof neutral spirits of your choice.

— anne brockhoff, kansascity, "Is your cocktail in season? Bartenders letting gardens dictate what's in your glass," 24 Apr. 2018
At Azalea Cove, upgrades will include a new drinking water system, the addition of bear-proof food receptacles and a new vehicle parking area.

— cathy locke, sacbee, "SMUD to upgrade campgrounds in Crystal Basin Recreation Area | The Sacramento Bee," 20 Apr. 2018
Their high-proof whiskies are designed with dilution and added water in mind, and the molecular interaction helps open up a bonus set of aromas.

— dan q. dao, GQ, "Japanese Whisky: A Guide for the Thirsty and Curious," 2 Apr. 2018
To future-proof Boracay’s natural beauty, the government has announced an unprecedented six-month closure of the island, set to begin next month and last through September, though an end date hasn't yet been confirmed.

— cynthia drescher, Condé Nast Traveler, "Boracay Set to Ban Tourists for Six Months During Island 'Rehabilitation'," 27 Mar. 2018

First Known Use of proof

1583

in the meaning defined at sense 1

See Words from the same year

NEW! Time Traveler

Other Alcoholic Beverage Terms

finish, gimlet, mull, sake, setup, sommelier, syllabub, vintner, wassail

proof

verb

proofed; proofing; proofs

transitive verb

1 a : 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

—

proofer

noun

See proof defined for English-language learners

Examples of proof in a Sentence

She proofed the story carefully.

Recent Examples of proof from the Web

Sky would play an important role in both Disney’s and Comcast’s future-proofing efforts.

— BostonGlobe.com, "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
Elder-proofing your house San Diego County caregivers can request free or low-cost minor home modifications, such as the installation of hand rails, grab bars, smoke detectors and handheld shower heads, from at least three nonprofit organizations.

— michele parente, sandiegouniontribune.com, "Resources for dementia caregivers," 27 Apr. 2018
It’s more the collective sum of features that makes these, in my opinion, a more appealing product than the first pair of glasses; from their smaller frame to better components to water-proofing.

— lauren goode, WIRED, "Snapchat Debuts New Spectacles. We Try Them on for Size," 26 Apr. 2018
Since the deadly July 2016 flood in Ellicott City, Ron Peters has spent $150,000 on restoration and flood proofing measures to not only repair the damage, but protect his three properties in historic Ellicott City against floodwaters.

— kate magill, Columbia Flier, "For flood-prone Ellicott City, study lays out ideas to make buildings more ‘resilient’," 23 Mar. 2018

First Known Use of proof

circa 1699

in the meaning defined at sense 1a

See Words from the same year

NEW! Time Traveler

Other Printing Terms

epigraph, errata, leader, mechanical, notch, tittle, underscore, widow

PROOF Defined for English Language Learners

proof

noun

: 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

proof

adjective

: designed or made to prevent or protect against something harmful

PROOF Defined for Kids

proof

noun \ ˈprüf \

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 : ¹test 2

Let's put her theory to the proof.

proof

adjective

: 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

Law Dictionary

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 : probate 1a