- joist⇄joist, noun, verb.
- joist⇄noun 1. one of the parallel beams of timber or steel which support the boards of a floor or ceiling.
Ex. They began again on the first floor picking up the top floorboards next to the outer wall, leaving the joists exposed (Harper's).
2. a s - joist⇄v.t. to provide with or lay across joists.