Joist n. : 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 v. t. : To fit or furnish with joists.

Example:
What is the maximum amount of space you can have between a floor Joist and ledger board when building a deck?

Taxonomy
I-joist, I-joists, rim joist, joists, free encyclopedia, flange, engineered wood, wood joist, lumber, bottom flange, wood product, solid wood, laminated veneer lumber, wood joists, dimensional lumber, top and bottom, nails, main beam.

Defination from the web:
joists. ... Another situation to look out for is matching the rim joist depth to the I-joist size. Improper matching can lead to too much strain on the I-joist. ...