# Fizeau-Foucault apparatus

> English word · Noun

## Definitions
1. Either of two types of instrument used to measure the speed of light.

## Etymology
Named after Hippolyte Fizeau and Léon Foucault.

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