noun.
The act corrugating; contraction into wrinkles or alternate ridges and grooves.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a ridge on a corrugated surface
noun.
the act of shaping into parallel ridges and grooves
Word Usage
"Slabs of sandstone and shale often retain what is called the ripple-mark -- that is, the corrugation of surface produced by the gentle agitation of shallow water over sand or mud."