[ahn pa-sahnt; French ahn pah-sahn]
(italics) French. in passing; by the way.
Chess. (used when a pawn that has moved two squares is captured by an opponent's pawn commanding the square that was passed.)
Origin of en passant
First recorded in 1655–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
in passing: in chess, said of capturing a pawn that has made an initial move of two squares to its fourth rank, bypassing the square where an enemy pawn on its own fifth rank could capture it. The capture is made as if the captured pawn had moved one square instead of two
Word Origin for en passant
C17: from French
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
French, literally "in passing," from present participle of passer "to pass" (see pass (v.)). In reference to chess, first attested 1818.
Online Etymology Dictionary, © 2010 Douglas Harper