Noun: sill sil
- Structural member consisting of a continuous horizontal timber forming the lowest member of a framework or supporting structure
"The carpenter replaced the rotted window sill"
- (geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock
"The geologist identified a prominent sill in the cliff face"
Derived forms: sills
Type of: rock, stone, structural member
Encyclopedia: Sill