Source : Webster's Revised Unabridged Dictionary (1913)

Underrun \Un`der*run"\, v. t.

   {To underrun a hose} (Naut.), to lift it up at one end, then
      walk along shifting one hand after another so that the
      water will run out. Underslung \Un"der*slung`\, Underhung
\Un"der*hung"\, a.
   Of an automobile body, suspended from the springs in such a
   manner that the frame of the chassis is below the axles, the
   object being to lower the center of gravity of the car.

Underhung \Un`der*hung"\, a.
   1. (Carp.) Resting on a track at the bottom, instead of being
      suspended; -- said of a sliding door. --Forney.

   2. Having the lower jaw projecting. --T. Hughes.

Source : WordNet®

underhung
     adj 1: supported from below especially resting on a track instead
            of suspended from above; "underhung sliding doors"
     2: having a lower part projecting beyond the upper; "an
        underhung jaw"; "undershot bulldog" [syn: {undershot}, {underslung}]