joist

joist
    n 1: beam used to support floors or roofs
    

Joist \Joist\ (joist), n. [OE. giste, OF. giste, F. g[^i]te, fr.
   gesir to lie, F. g['e]sir. See {Gist}.] (Arch.)
   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.
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Joist \Joist\, v. t. [imp. & p. p. {Joisted}; p. pr. & vb. n.
   {Joisting}.]
   To fit or furnish with joists. --Johnson.
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