The Collaborative International Dictionary of English v.0.48:

Crumple \Crum"ple\ (kr[u^]m"p'l), v. t. [imp. & p. p. Crumpled
   (-p'ld); p. pr. & vb. n. Crumpling (-pl[i^]ng).] [Dim. fr.
   crump, a.]
   To draw or press into wrinkles or folds; to crush together;
   to rumple; as, to crumple paper.
   [1913 Webster]

         They crumpled it into all shapes, and diligently
         scanned every wrinkle that could be made. --Addison.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Crumple \Crum"ple\, v. i.
   To contract irregularly; to show wrinkles after being crushed
   together; as, leaves crumple.
   [1913 Webster]

WordNet (r) 3.0 (2006):

crumple
    v 1: fall apart; "the building crumbled after the explosion";
         "Negotiations broke down" [syn: crumble, crumple,
         tumble, break down, collapse]
    2: fold or collapse; "His knees buckled" [syn: buckle,
       crumple]
    3: to gather something into small wrinkles or folds; "She
       puckered her lips" [syn: pucker, rumple, cockle,
       crumple, knit]
    4: become wrinkled or crumpled or creased; "This fabric won't
       wrinkle" [syn: rumple, crumple, wrinkle, crease,
       crinkle]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "crumple":
   bend, break, bristle, buckle, cave, cocker, cockle, collapse,
   contort, corrugate, corrugation, crankle, crease, crimp, crimple,
   crinkle, crook, crush, distort, fold, fold up, furrow, gnarl, go,
   knit, knot, mangle, pucker, purse, ridge, rimple, ripple, rivel,
   ruck, ruckle, ruffle, rumple, screw, scrunch, set on edge, shirr,
   spring, turn, turn awry, twist, wad, warp, wimple, wrench, wrest,
   wring, wrinkle, writhe, yield