SILL

n. horizontal piece beneath a window; threshold, doorsill, horizontal piece at the base of a doorway; horizontal foundational element (i.e. beam, block, etc.)

Sill may refer to:Sill (geology), a tabular mass of igneous rock that has been intruded laterally between layers of older rockArchitecture, a sill is the bottom edge of a window or doorConstruction, the bottom horizontal member of a wall or building to which vertical members are attachedSill River, a tributary to the Inn River in Austria
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Noun
1. structural member consisting of a continuous horizontal timber forming the lowest member of a framework or supporting structure
(hypernym) structural member
(hyponym) doorsill, doorstep, threshold
2. (geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock
(hypernym) rock, stone
(classification) geology

(n.)
The timber or stone on which a window frame stands; or, the lowest piece in a window frame.
  

(n.)
The timber or stone at the foot of a door; the threshold.
  

(n.)
The shaft or thill of a carriage.
  

(n.)
The floor of a gallery or passage in a mine.
  

(n.)
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.
  

(n.)
A young herring.
  

(n.)
A piece of timber across the bottom of a canal lock for the gates to shut against.
  

A horizontal beam forming the bottom of an entrance to a lock. (TNDOT1)