Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun sill

2 senses of sill

Sense 1
sill -- (structural member consisting of a continuous horizontal timber forming the lowest member of a framework or supporting structure)
       => structural member -- (support that is a constituent part of any structure or building)

Sense 2
sill -- ((geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock)
       => rock, stone -- (a lump or mass of hard consolidated mineral matter; "he threw a rock at me")