joist /ˈʤɔɪst/
  托梁,桁
  Joist, v. t. [imp. & p. p. Joisted; p. pr. & vb. n. Joisting.] To fit or furnish with joists.
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  Joist n.  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.
  joist
       n : beam used to support floors or roofs