early 14c.,  cromplen, crumplen, "press into irregular folds, rumple, wrinkle," also intransitive, "contract into wrinkles, shrink, shrivel," frequentative of crumpen "to curl up" (from Old English crump "bent, crooked"), from Proto-Germanic *krumbo- "to press, squeeze, compress" (source also of German krumm "crooked, warped"). Related: Crumpled; crumpling.

also crummhorn, "A medieval musical instrument of the clarinet class, having a curved tube and a melancholy sound" [Century Dictionary], 1864, from German, literally "crooked horn," from krumm "curved, crooked" (8c.), from a West Germanic *krumba- (compare Old English crumb, crump "crooked, bent, stooped," source of crumple); for second element see horn (n.).

sort of tea-cake, 1690s, perhaps from crompid cake "wafer," literally "curled-up cake" (1382; Wyclif's rendering of Hebrew raqiq in Exodus xxix.23), from crompid, past participle of crumpen "curl up" (see crumple (v.)). Alternative etymology is from Celtic (compare Breton krampoez "thin, flat cake"). Slang meaning "woman regarded as a sex object" is first recorded 1936.

1746, "cross-tempered," probably from the frumps (n.) "bad temper" (1660s) and an earlier verb meaning "to mock, browbeat" (1550s), of obscure origin, perhaps imitative of a sneer or derisive snort. See also frump. Sense of "sour-looking, unfashionable" is from 1825, but this may be a shortening of frumple "to wrinkle, crumple" (late 14c.), from Middle Dutch verrompelen "to wrinkle," from ver- "completely" + rompelen "to rumple." Related: Frumpily; frumpiness.