underhung

adjective

1. Anatomy.
   1. (of the lower jaw) projecting beyond the upper jaw.
   2. having the lower jaw so projecting.
2. resting on a track beneath instead of being overhung, as a sliding door.

adjective

1. (of the lower jaw) projecting beyond the upper jaw; undershot
2. (of a sliding door, etc) supported at its lower edge by a track or rail