flat iron

noun

1

: a device used for straightening hair by pressing and pulling sections between two heated metal or ceramic, flat, rectangular plates

2

usually flatiron

ˈflat-ˌī(-ə)rn 

old-fashioned : iron sense 2a

Examples of flat iron in a Sentence

Recent Examples on the Web

To get a pin-straight finish, Korab recommends applying a smoothing lotion or oil and doing a sleek blowout, followed by a flat iron. — Omenaa Boakye, InStyle, 19 Sep. 2026

Sprays are also convenient for dry-hair touch-ups before a curling iron or flat iron. — Polly Blitzer, Glamour, 9 Sep. 2026

Allure content director Sophie Panych, whose hair is naturally fine and straight, will occasionally touch things up with a flat iron. — Marci Robin, Allure, 21 Aug. 2026

Now with its new flat iron, the styling suite is complete for safely silkening textured strands. — Brianna J. Heath, Vogue, 14 Aug. 2026

Word History

First Known Use

1743, in the meaning defined at sense 2

Rhymes for flat iron

• flatiron
• gridiron

Kids Definition

flatiron

noun

flat·​iron -ˌī(-ə)rn 

: iron entry 1 sense 2c