[ foo-koh ]

  1. Jean Ber·nard Lé·on [zhahnber-narley-awn], /ʒɑ̃ bɛrˈnar leɪˈɔ̃/, 1819–68, French physicist.

  2. Michel [mee-shel], /miˈʃɛl/, 1926–84, French philosopher.

Words Nearby Foucault Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use Foucault in a sentence

  • Wheatstone's device of the revolving mirror was afterwards employed by Foucault and Fizeau to measure the velocity of light.

  • The most convenient test is that of Foucault, a simple appliance for the purpose being shown in the figure .

    On Laboratory Arts | Richard Threlfall
  • It is well,” replied a great grey tom, whom Jean took to be the leader; “pass on, Jean Foucault.

  • The velocity of light was experimentally found, in 1862, by Fizeau and Foucault, each using an independent method.

    History of Astronomy | George Forbes
  • Even the arc-light that Foucault produced in 1844 was not utilized then.

    Invention | Bradley A. Fiske

British Dictionary definitions for Foucault


/ (French fuko) /

  1. Jean Bernard Léon (ʒɑ̃ bɛrnar leɔ̃). 1819–68, French physicist. He determined the velocity of light and proved that light travels more slowly in water than in air (1850). He demonstrated by means of the pendulum named after him the rotation of the earth on its axis (1851) and invented the gyroscope (1852)

  2. Michel . 1926–84, French philosopher and historian of ideas. His publications include Histoire de la folie (1961) and Les Mots et les choses (1966)

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for Foucault


[ fōō-kō ]

  1. French physicist who determined that light travels more slowly in water than in air, confirming predictions made by the wave theory of light. In 1850 Foucault also measured the absolute velocity of light. In 1851, by using a type of pendulum that is now named after him, Foucault demonstrated the rotation of the Earth, and in 1852 perfected a gyroscope for the same purpose.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.