sills

noun

1. 1.(also window sill) A horizontal slat which forms the base of a window.
2. 2.A horizontal, structural member of a building near ground level on a foundation or pilings or lying on the ground in earth-fast construction and bearing the upright portion of a frame. Also called a ground plate, groundsill, sole, sole-plate, mudsill. An interrupted sill fits between posts instead of being below and supporting the posts in timber framing.
3. 3.A horizontal layer of igneous rock between older rock beds.
4. 4.A piece of timber 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.