proof

proof — noun

1. facts or documents that establish beyond doubt that a particular claim is true o

1.nounB2
Definition

facts or documents that establish beyond doubt that a particular claim is true or that a given situation exists

Example

The police found proof that Noa had been at the bank that morning.

proof + that-clause for factual certainty

Scientists are still searching for proof of ancient life on the red planet.

proof of + noun phrase

Common collocations
  • conclusive proof
  • proof positive
  • burden of proof
  • standard of proof
  • documentary proof
Synonyms
  • evidence

    wider term; evidence suggests something may be true, while proof aims to establish it beyond doubt

  • confirmation

    focuses on verifying something already suspected or known

  • verification

    more formal; often used in scientific or technical contexts

Antonyms
  • disproof

    formal term for evidence that shows something is false

Grammar Patterns

proof + that-clause

proof of + noun phrase

Usage Note

Uncountable in most contexts ('We need proof'), but countable when referring to specific documents or pieces of evidence ('She collected several proofs of her identity').

Common Mistakes

I have a proof that he is lying.
I have proof that he is lying.
'proof' is usually uncountable; don't add 'a' unless referring to a specific document.
There is no prove that she was there.
There is no proof that she was there.
'proof' is a noun; 'prove' is the verb form.

2. a formal chain of reasoning that confirms the correctness of a mathematical clai

2.nounB2
Definition

a formal chain of reasoning that confirms the correctness of a mathematical claim or scientific proposition

Example

The mathematician published her proof of the theorem in a leading journal.

proof of + abstract concept

Students had to write a complete proof for each geometry problem on the exam.

complete / write a proof

Common collocations
  • mathematical proof
  • formal proof
  • proof by contradiction
  • proof of concept
Synonyms
  • demonstration

    broader term; can refer to showing how something works, not just logical reasoning

  • argument

    less formal; may not have the same rigor as a mathematical proof

Usage Note

Countable — you can say 'a proof' or 'proofs' in this sense. Unlike sense 1, this refers to a structured logical argument rather than general evidence.

3. an early printed version of a book or article that writers and editors examine a

3.nounB1
Definition

an early printed version of a book or article that writers and editors examine and correct prior to the production of the finished publication

Example

The editor sent the proof back to the printer with several corrections marked in red.

send a proof back for corrections

Stephanie was asked to check the page proofs of her novel before the deadline.

page proofs (compound noun)

Common collocations
  • page proofs
  • galley proof
  • first proof
  • correct the proofs
Synonyms
  • galley proof

    a specific type of early proof, usually in a single column before page layout

  • page proof

    a proof arranged in final page format

Usage Note

Common in publishing and journalism. Related verbs are 'proofread' (to check proofs) and 'proof' (to make something waterproof — a different sense).

Common Mistakes

I need to proof the document for errors.
I need to proofread the document for errors.
'proof' as a verb in publishing is rare; use 'proofread'.

4. a system of measuring how much alcohol is in a drink, where a higher number mean

4.nounC1
Definition

a system of measuring how much alcohol is in a drink, where a higher number means stronger alcohol; in the US, 100 proof equals 50% alcohol by volume

Example

This bottle of bourbon is 80 proof, which is standard for most whiskeys.

number + proof (measurement phrase)

The bartender warned that 100 proof rum is much stronger than the usual kind people mix with cola.

Common collocations
  • 80 proof
  • 100 proof
  • proof spirit

Usage Note

The US and UK systems differ slightly. In the UK, proof historically referred to a specific gravity test, but modern labeling uses alcohol-by-volume (ABV) instead. In everyday US conversation, the proof number is simply double the ABV percentage.

Idioms

the proof of the pudding is in the eating

idiom

You cannot truly judge the quality or value of something until you try it or use it for yourself.

The new software looks good on paper, but the proof of the pudding is in the eating — we need to test it with real users.

Amani was skeptical about the recipe, but the proof of the pudding is in the eating, and everyone asked for seconds.

proof positive

idiom

clear, absolute, and undeniable evidence that settles a question beyond any doubt.

The CCTV footage was proof positive that the suspect had been near the building at midnight.

Her first-place finish in the race was proof positive that months of hard training had paid off.

burden of proof

idiom

the duty of one party in a legal case or debate to provide sufficient evidence to support their claim, because without it the claim will be rejected.

In a criminal trial, the burden of proof lies with the prosecution, not the defense.

The reporter knew the burden of proof was on her to show that the documents were authentic.

be living proof of something/that…

idiom

To show that something is true through your own actions or qualities.

Maya's success is living proof that hard work pays off.

Are these results living proof of the team's dedication?

proof — adjective

proof — verb

proof — suffix

Word family

  • prove
    verbB1
  • proven
    adjectiveB2
  • proofread
    verbB2
  • proofreader
    nounB2
  • waterproof
    adjectiveB1
  • bulletproof
    adjectiveB2
  • foolproof
    adjectiveC1
  • disproof
    nounC2

Synonym discussion

Sense: noun/1

Evidence and proof are closely related but differ in certainty. Evidence refers to any information that suggests something might be true — it can be weak, circumstantial, or incomplete. Proof, on the other hand, is evidence that is strong enough to establish something beyond reasonable doubt. In a courtroom, prosecutors present evidence hoping to meet the standard of proof required for a conviction. Confirmation is narrower: it is additional evidence that supports something already believed or suspected, like a DNA test confirming a suspect's identity. Verification is the most formal and procedural — it involves checking that facts, data, or systems meet a specific standard, such as verifying a user's email address before granting access. In everyday use, 'I have proof' sounds far more certain than 'I have evidence.'

evidence ↗proof ↗confirmation ↗verification ↗

Common collocations

Nouns

Adverbs

Phrases

  • proof of concept
  • proof of purchase
  • proof of identity

Prepositions

Etymology

LatinOld FrenchMiddle EnglishEnglish

The word 'proof' entered English through Old French 'prove' and 'preuve', which came from Late Latin 'proba' meaning 'a testing, a proof.' The Latin root goes back to 'probare' — to test, approve, or demonstrate to be good — which is also the source of 'prove,' 'probe,' and 'probable.' The spelling shifted from 'prove' to 'proof' in Middle English, influenced by the Latin spelling. The adjective sense relating to alcohol resistance dates from the 18th century, when the British navy tested the strength of rum by mixing it with gunpowder — if it still burned, it was 'proof' that the alcohol content was high enough.