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.

Source : WordNet®

underslung
     adj 1: supported from above especially in a vehicle having springs
            attached to the axle from below
     2: having a lower part projecting beyond the upper; "an
        underhung jaw"; "undershot bulldog" [syn: {underhung}, {undershot}]
     3: having a low center of gravity; built low to the ground
        [syn: {squat}]