cor·ru·gate /ˈkɔrəˌget, ˈkɑr-/
  (vt.)使起皺,成波狀(vi.)縮成皺狀(a.)有皺的,起皺的,波狀的
  Cor·ru·gate a.  Wrinkled; crumpled; furrowed; contracted into ridges and furrows.
  Cor·ru·gate v. t. [imp. & p. p. Corrugated p. pr. & vb. n. Corrugating ] 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.
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  corrugate
       v : fold into ridges; "corrugate iron"