# event horizon

> English word · Noun · IPA /əˈvɛnt həˈɹaɪ.zən/

## Definitions
1. The gravitational sphere of a black hole within which the escape velocity is greater than the speed of light.
2. The furthest distance in the past of the universe from which light signals from an event can reach an observer at later times.
3. A point of no return.

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