sill
//sɪl//
Noun
sillSingular
sillsPlural
1
A horizontal piece of wood, stone, or metal at the bottom of a window or door frame.
The cat likes to sit on the window sill and watch the birds outside.
2
A horizontal structural member forming the lowest part of a framework or supporting structure, especially the base of a wall or building.
The carpenter inspected the sill before building the wall.
3
(Geology) A flat sheet of igneous rock intruded between and parallel to existing layers of rock.
The geologist discovered a sill of basalt between the sedimentary layers.