sill

Short definition from Wiktionary

Noun

1. 1
   A breast wall; window breast; horizontal brink which forms the base of a window.
2. 2
   A threshold; horizontal structural member of a building near ground level on a foundation or pilings, or lying on the ground, and bearing the upright portion of a frame; a sill plate.
3. 3
   A stratum of rock, especially an intrusive layer of igneous rock lying parallel to surrounding strata.
4. 4
   A threshold or brink across the bottom of a canal lock for the gates to shut against.
5. 5
   A raised area at the base of the nasal aperture in the skull.
6. 6
   The inner edge of the bottom of an embrasure.
7. 7
   A young herring.
8. 8
   The shaft or thill of a carriage.

Adjective

1. 1
   Silly.

Proper noun

1. 1
   A surname.