Sill \Sill\ (s[i^]l), n. [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.]

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. [1913 Webster]

Sill course (Arch.), a horizontal course of stone, terra cotta, or the like, built into a wall at the level of one or more window sills, these sills often forming part of it. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

Sill \Sill\, n. [Cf. Thill.]

The shaft or thill of a carriage. [Prov. Eng.]

[1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

Sill \Sill\, n. [Cf. 4th Sile.]

A young herring. [Eng.]

[1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

45 Moby Thesaurus words for "sill": base, basement, basis, bearing wall, bed, bedding, bedrock, doorsill, doorstone, floor, flooring, fond, footing, foundation, fundament, fundamental, ground, grounds, groundsel, groundwork, hardpan, mudsill, pavement, principle, radical, riprap, rock bottom, rudiment, seat, solid ground, solid rock, stereobate, stylobate, substratum, substruction, substructure, terra firma, threshold, underbuilding, undercarriage, undergirding, underpinning, understruction, understructure, window sill

Source: Moby Thesaurus II by Grady Ward, 1.0
 

sill

Source: WordNet (r) 2.0
 

Sill \Sill\, n. [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.]

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 course (Arch.), a horizontal course of stone, terra cotta, or the like, built into a wall at the level of one or more window sills, these sills often forming part of it.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Sill \Sill\, n. [Cf. Thill.]

The shaft or thill of a carriage. [Prov. Eng.]

Source: Webster's Revised Unabridged Dictionary (1913)
 

Sill \Sill\, n. [Cf. 4th Sile.]

A young herring. [Eng.]

Source: Webster's Revised Unabridged Dictionary (1913)