General English

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.


  • herring

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’.