Corrugating

from The Collaborative International Dictionary of English v.0.48
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.
   [1913 Webster]

   {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.
      [1913 Webster]
    

grant@antiflux.org