Corrugate

Part of speech: verb (v.)

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.

Part of speech: adjective (a.)

Wrinkled; crumpled; furrowed; contracted into ridges and furrows.