Joist
Joist (joist) , noun
[Old English giste, Old French giste, French gîte, from gesir to lie, French gésir. See Gist.]
(Architecture) A piece of timber laid horizontally, or nearly so, to which the planks of the floor, or the laths or furring strips of a ceiling, are nailed; -- called, according to its position or use, binding joist, bridging joist, ceiling joist, trimming joist, etc. See Illust. of Double-framed floor, under Double, a.
Joist , transitive verb
To fit or furnish with joists. — Johnson