# trapdoor function

> English word · Noun

## Definitions
1. A function that is easy to compute in one direction but difficult to compute in the opposite direction (finding its inverse) without special information.

## Etymology
From the idea that it is easy to fall through a trapdoor but difficult to climb back out.

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