# functor

> English word · Noun · IPA /ˈfʌŋktə/ · frequency rank #79,529

## Definitions
1. A function word.
2. A function object.
3. A category homomorphism; a morphism from a source category to a target category which maps objects to objects and arrows to arrows (either covariantly or contravariantly), in such a way as to preserve morphism composition and identities.
4. A structure allowing a function to apply within a generic type, in a way that is conceptually similar to a functor in category theory.

## Etymology
From function, modeled after factor.

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