Source : Webster's Revised Unabridged Dictionary (1913)

Corrugate \Cor"ru*gate\ (k?r"r?-g?t), a. [L. corrugatus, p. p.
   of corrugare; cor-+ rugare to wrinkle, ruga wrinkle; of
   uncertain origin.]
   Wrinkled; crumpled; furrowed; contracted into ridges and
   furrows.

Corrugate \Cor"ru*gate\ (-g?t), v. t. [imp. & p. p. {Corrugated}
   (-g?`t?d); p. pr. & vb. n. {Corrugating} (-g?`t?ng).]
   To form or shape into wrinkles or folds, or alternate ridges
   and grooves, as by drawing, contraction, pressure, bending,
   or otherwise; to wrinkle; to purse up; as, to corrugate
   plates of iron; to corrugate the forehead.

   {Corrugated iron}, sheet iron bent into a series of alternate
      ridges and grooves in parallel lines, giving it greater
      stiffness.

   {Corrugated paper}, a thick, coarse paper corrugated in order
      to give it elasticity. It is used as a wrapping material
      for fragile articles, as bottles.

Source : WordNet®

corrugate
     v : fold into ridges; "corrugate iron"