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.-the timber or stone at the foot of a door; the threshold.-the timber or stone on which a window frame stands; or, the lowest piece in a window frame.-the floor of a gallery or passage in a mine.-a piece of timber across the bottom of a canal lock for the gates to shut against.-the shaft or thill of a carriage.-a young herring.