# Cauchy horizon

> English word · Noun

## Definitions
1. A lightlike boundary of the domain of validity of a Cauchy problem, in which one side of the horizon contains closed space-like geodesics and the other side contains closed timelike geodesics.

## Etymology
Named after Augustin-Louis Cauchy

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