WordReference Random House Unabridged Dictionary of American English © 2026
box′ sill′, [Carpentry.]
- Buildinga sill for a building frame, composed of a plate resting on the basement wall and a joist or header at the outer edge of the plate, as well as a soleplate for the studs resting either directly on the joists or on the rough flooring. Cf. L sill.
'box sill' also found in these entries (note: many are not synonyms or translations):