The Collaborative International Dictionary of English v.0.48:

Corrugation \Cor`ru*ga"tion\ (k?r`r?-g?"sh?n), n. [Cf. F.
   corrugation.]
   The act corrugating; contraction into wrinkles or alternate
   ridges and grooves.
   [1913 Webster]

WordNet (r) 3.0 (2006):

corrugation
    n 1: a ridge on a corrugated surface
    2: the act of shaping into parallel ridges and grooves

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "corrugation":
   bezel, broken ground, broken water, chamfer, chase, chink, chop,
   cockle, corduroy, corduroy road, crack, crankle, cranny, crease,
   crimp, crinkle, crumple, cut, dado, engraving, flute, fluting,
   fold, furrow, gash, goose bumps, goose pimples, gooseflesh, gouge,
   groove, horripilation, incision, lop, microgroove, plica, pucker,
   rabbet, ridge, rifling, rimple, ripple, rivel, rough, ruck, rumple,
   rut, sandpaper, score, scratch, slit, streak, stria, striation,
   sulcation, sulcus, washboard, well-worn groove, wimple, wrinkle