# reduction

> English word · Noun · IPA /ɹɪˈdʌk.ʃən/ · frequency rank #3,716

## Definitions
1. The act, process, or result of reducing.
2. The amount or rate by which something is reduced, e.g. in price.
3. A reaction in which electrons are gained and valence is reduced; often by the removal of oxygen or the addition of hydrogen.
4. The process of rapidly boiling a sauce to concentrate it.
5. The rewriting of an expression into a simpler form.
6. A transformation of one problem into another problem, such as mapping reduction or polynomial-time reduction.
7. An arrangement for a far smaller number of parties, e.g. a keyboard solo based on a full opera.
8. A philosophical procedure intended to reveal the objects of consciousness as pure phenomena. (See phenomenological reduction.)
9. A medical procedure to restore a fracture or dislocation to the correct alignment, usually with a closed approach but sometimes with an open approach (surgery).
10. A reduced price of something by a fraction or decimal.
11. The ratio of a material's change in thickness compared to its thickness prior to forging and/or rolling.
12. A religious settlement created during a mission by Spanish or Portuguese colonists with the intent of evangelizing Christianity to the local population.

## Etymology
From Middle English reduccion, a borrowing from Old French reducion, from Latin reductiō, reductiōnem. Equivalent to reduce + -tion.

## Easily confused with
- **rejection** (https://plainspell.com/en/vs/reduction-vs-rejection)
- **resection** (https://plainspell.com/en/vs/reduction-vs-resection)
- **reductive** (https://plainspell.com/en/vs/reduction-vs-reductive)
- **reaction** (https://plainspell.com/en/vs/reaction-vs-reduction)

## Common misspellings (14)
`erduction`, `rdeuction`, `redcution`, `redduction`, `reducction`, `reduciton`, `reducsion`, `reductino`, `reductionn`, `reductoin`, `reducttion`, `redutcion`, `reudction`, `rreduction`

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