# fail closed

> English word · Verb

## Definitions
1. Of an access control system: to automatically block all traffic in the case of a failure. For example, an electronic safe becoming impossible to unlock in the event of a power outage.

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