crumple

verb

1. 1

   become wrinkled or crumpled or creased

   This fabric won't wrinkle

2. 2

   to gather something into small wrinkles or folds

   She puckered her lips

3. 3

   fold or collapse

   His knees buckled

4. 4

   fall apart

   the building crumbled after the explosion

   Negotiations broke down