corrugation (n.)

"to wrinkle, to draw or contract into folds," 1610s, from Latin corrugatus, past participle of corrugare "to make full of wrinkles, wrinkle very much" (also "produce loathing, cause disgust"), from assimilated form of com-, here perhaps an intensive prefix (see com-), + rugare "to wrinkle," from ruga "crease, groove," which is of uncertain origin (see rugae).