[ joist ]
/ dʒɔɪst /


any of a number of small, parallel beams of timber, steel, reinforced concrete, etc., for supporting floors, ceilings, or the like.

verb (used with object)

to furnish with or fix on joists.


Origin of joist

1325–75; Middle English giste < Old French < Latin *jacitum support, noun use of neuter of Latin jacitus (past participle of jacēre to lie), equivalent to jaci- variant stem + -tus past participle suffix
Related formsjoist·less, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for joist

British Dictionary definitions for joist


/ (dʒɔɪst) /


a beam made of timber, steel, or reinforced concrete, used in the construction of floors, roofs, etcSee also rolled-steel joist


(tr) to construct (a floor, roof, etc) with joists

Word Origin for joist

C14: from Old French giste beam supporting a bridge, from Vulgar Latin jacitum (unattested) support, from jacēre to lie
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

Word Origin and History for joist



early 14c. (late 13c. in Anglo-Latin), from Old French giste "beam supporting a bridge" (Modern French gîte), noun use of fem. past participle of gesir "to lie," from Latin iacere "to lie, rest," related to iacere "to throw" (see jet (v.)). Notion is of wooden beam on which boards "lie down."

Online Etymology Dictionary, © 2010 Douglas Harper