# proof

> English word · Noun · IPA /pɹuːf/ · frequency rank #2,052

## Definitions
1. An effort, process, or operation designed to establish or discover a fact or truth; an act of testing; a test; a trial.
2. The degree of evidence which convinces the mind of any truth or fact, and produces belief; a test by facts or arguments which induce, or tend to induce, certainty of the judgment; conclusive evidence; demonstration.
3. The quality or state of having been proved or tried; firmness or hardness which resists impression, or does not yield to force; impenetrability of physical bodies.
4. Experience of something.
5. Firmness of mind; stability not to be shaken.
6. A proof sheet; a trial impression, as from type, taken for correction or examination.
7. A limited-run high-quality strike of a particular coin, originally as a test run, although nowadays mostly for collectors' sets.
8. A sequence of statements consisting of axioms, assumptions, statements already demonstrated in another proof, and statements that logically follow from previous statements in the sequence, and which concludes with a statement that is the object of the proof.
9. A process for testing the accuracy of an operation performed. Compare prove, transitive verb, 5.
10. Armour of excellent or tried quality, and deemed impenetrable; properly, armour of proof.
11. A measure of the alcohol content of liquor. Originally, in Britain, 100 proof was defined as 57.1% by volume (no longer used). In the US, 100 proof means that the alcohol content is 50% of the total volume of the liquid; thus, perfectly pure absolute alcohol would be 200 proof.

## Etymology
From Middle English proof, from Old French prove, from Late Latin proba (“a proof”), from Latin probō (“to prove”); see prove; compare also the doublet probe.

## Easily confused with
- **pros** (https://plainspell.com/en/vs/proof-vs-pros)
- **prop** (https://plainspell.com/en/vs/proof-vs-prop)
- **Prot** (https://plainspell.com/en/vs/proof-vs-prot)
- **proud** (https://plainspell.com/en/vs/proof-vs-proud)
- **prove** (https://plainspell.com/en/vs/proof-vs-prove)
- **proxy** (https://plainspell.com/en/vs/proof-vs-proxy)
- **props** (https://plainspell.com/en/vs/proof-vs-props)
- **prose** (https://plainspell.com/en/vs/proof-vs-prose)
- **proto** (https://plainspell.com/en/vs/proof-vs-proto)
- **Pryor** (https://plainspell.com/en/vs/proof-vs-pryor)
- **Provo** (https://plainspell.com/en/vs/proof-vs-provo)
- **prowl** (https://plainspell.com/en/vs/proof-vs-prowl)
- **proton** (https://plainspell.com/en/vs/proof-vs-proton)
- **proofs** (https://plainspell.com/en/vs/proof-vs-proofs)
- **pro** (https://plainspell.com/en/vs/pro-vs-proof)
- **poo** (https://plainspell.com/en/vs/poo-vs-proof)
- **poor** (https://plainspell.com/en/vs/poor-vs-proof)
- **pool** (https://plainspell.com/en/vs/pool-vs-proof)
- **prom** (https://plainspell.com/en/vs/prom-vs-proof)
- **poop** (https://plainspell.com/en/vs/poop-vs-proof)

## Common misspellings (7)
`porof`, `pproof`, `prof`, `profo`, `prooff`, `prroof`, `rpoof`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/proof