Cars & Driving
- noun a longitudinal box section member of the body shell at floor level, located below the doors
- noun a box section crossmember just below the lower edge of the bootlid (when closed)
- The horizontal member of the bottom of a window or exterior door frame.
- As applied to general construction, the lowest member of the frame of the structure, resting on the foundation and supporting the frame. See also mudsill.
Origin & History of “sill”
Sill originally denoted the ‘foundation of a wall’. Not until the 15th century was it used for the ‘base of a window-frame’. It is related to German schwelle ‘threshold’ and possibly also to English sole ‘underside of the foot’.