Flat iron
A heated tool with two flat plates that are clamped over hair to press it straight.
Also: straightener, hair iron
A flat iron, or straightener, has two heated plates that close over a section of hair and glide down it, pressing out waves and curls. It can also bend hair into waves with a twist of the wrist. The heat changes the weaker bonds in the hair only for a while, so the hair goes back to its pattern when it gets wet. Using high heat too often can cause dryness and breakage, so stylists use the lowest heat that works.