Corrugate

Pronunciation: -g?t
v. t.
  1. 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.
    2. 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.