Source : Webster's Revised Unabridged Dictionary (1913)

Slump \Slump\, v. i. [imp. & p. p. {Slumped}; p. pr. & vb. n.
   {Slumping}.] [Scot. slump a dull noise produced by something
   falling into a hole, a marsh, a swamp.]
   To fall or sink suddenly through or in, when walking on a
   surface, as on thawing snow or ice, partly frozen ground, a
   bog, etc., not strong enough to bear the person.

         The latter walk on a bottomless quag, into which
         unawares they may slump.                 --Barrow.

Source : WordNet®

slumped
     adj : with shoulders drooping [syn: {slouched}, {slouching}]