sill Meaning, Definition & Usage

  1. noun structural member consisting of a continuous horizontal timber forming the lowest member of a framework or supporting structure
  2. noun (geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock

WordNet

Sill noun
Etymology
OE. sille, sylle, AS. syl, syll; akin to G. schwelle, OHG. swelli, Icel. syll, svill, Sw. syll, Dan. syld, Goth. gasuljan to lay a foundation, to found.
Definitions
  1. The basis or foundation of a thing; especially, a horizontal piece, as a timber, which forms the lower member of a frame, or supports a structure; as, the sills of a house, of a bridge, of a loom, and the like. Hence: (a) The timber or stone at the foot of a door; the threshold. (b) The timber or stone on which a window frame stands; or, the lowest piece in a window frame. (c) The floor of a gallery or passage in a mine. (d) A piece of timber across the bottom of a canal lock for the gates to shut against.
Sill noun
Etymology
Cf. Thill.
Definitions
  1. The shaft or thill of a carriage. Prov. Eng.
Sill noun
Etymology
Cf. 4th Sile.
Definitions
  1. A young herring. Eng.

Webster 1913