sill

The horizontal member that bears the upright portion of a frame, especially the horizontal member that forms the base of a window.

An approximately horizontal sheet of igneous rock intruded between older rock beds.

A young herring.

The thill or shaft of a carriage.

A variant of sell.

A stone or piece of timber on which a structure rests; a block forming a basis or foundation: as, the sills of a house, of a bridge, of a loom; more specifically, a horizontal piece of timber of the frame of a building, or of wood or stone at the bottom of a framed case, such as that of a door or window; in absolute use, a door-sill. See door-sill, ground-sill, mudsill, port-sill, window-sill.

In fortification, the inner edge of the bottom or sole of an embrasure. See diagram under embrasure.

In mining: The floor of a gallery or passage in a mine.

A term used by miners in the lead districts of the north of England as nearly equivalent to bed or stratum. Thus, the basaltic sheets intercalated in the mountain-limestone are called whin –sills.

A young herring.