sill

Definitions of sill
1

n structural member consisting of a continuous horizontal timber forming the lowest member of a framework or supporting structure

Types:
doorsill, doorstep, threshold
the sill of a door; a horizontal piece of wood or stone that forms the bottom of a doorway and offers support when passing through a doorway
windowsill
the sill of a window; the horizontal member at the bottom of the window frame
Type of:
structural member
support that is a constituent part of any structure or building

n (geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock

Type of:
rock, stone
a lump or mass of hard consolidated mineral matter

Sign up, it's free!

Whether you're a student, an educator, or a lifelong learner, Vocabulary.com can put you on the path to systematic vocabulary improvement.