a joint between two parts of a structure, machine, etc., permitting expansion, as from heat, without structural damage.
Origin of expansion joint
First recorded in 1840–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for expansion joint
engineering a gap in steel or concrete to allow for thermal expansion
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