Merriam-Webster's Collegiate® Dictionary, 11th Edition
RUMPLE
I. noun
Date: circa 1520
fold , wrinkle ,
II. verb (rumpled; rumpling)
Etymology: Dutch rompelen; akin to Old High German rimpfan to wrinkle
Date: 1603
transitive verb wrinkle , crumple , to make unkempt ; tousle , intransitive verb to become rumpled