The Collaborative International Dictionary of English v.0.48:

Crump \Crump\ (kr[u^]mp), a. [AS. crumb stooping, bent down;
   akin to OHG. chrumb, G. krumm, Dan. krum, D. krom, and E.
   cramp.]
   1. Crooked; bent. [Obs.]
      [1913 Webster]

            Crooked backs and crump shoulders.    --Jer. Taylor.
      [1913 Webster]

   2. Hard or crusty; dry baked; as, a crump loaf. [Prov. Eng. &
      Scot.] --Hallivell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

crump
    v 1: make a noise typical of an engine lacking lubricants [syn:
         crump, thud, scrunch]
    2: bombard with heavy shells
    3: explode heavily or with a loud dull noise