v. & n.
v. 1 tr. & intr. (often foll. by up) a crush or become crushed into creases. b ruffle, wrinkle. 2 intr. (often foll. by up) collapse, give way.
n. a crease or wrinkle. crumple zone a part of a motor vehicle, esp. the extreme front and rear, designed to crumple easily in a crash and absorb impact. crumply adj.
[ obs. crump (v. & adj.) (make or become) curved ]