|Origin:||crump 'to curl up' (14-19 centuries), from crump, crumb 'bent' (11-18 centuries), from Old English|
1 [intransitive and transitive] also crumple up
to crush something so that it becomes smaller and bent, or to be crushed in this way:
Dan tore the page out, crumpled it, and threw it in the wastepaper basket.
if your face crumples, you suddenly look sad or disappointed, as if you might cry
if your body crumples, you fall down in an uncontrolled way
The blow hit him in the head and he crumpled to the ground.