A hairgrip is a small, thin piece of metal — often with a little wave or crinkle — that slides into the hair and holds a piece of it in place. British English uses this word; in American English the same thing is usually a bobby pin. Though actually, people also say hairpin, but a classic hairpin is often a simple U-shape, and a hairgrip / bobby pin is the tighter, ridged kind that grips. It is a woman’s everyday tool in a lot of older dictionary lines, but anyone with long hair uses them: to pin back a fringe, hold a bun, or keep a loose bit off the face. They are small enough to lose down the sofa. The word is ordinary in Britain, slightly unfamiliar in American classrooms, and not slang. It is the clip itself, not the hairstyle.

一字夾（英式說法；美式叫 bobby pin。台灣說「一字夾」比籠統的「髮夾」更準，髮夾還包括鯊魚夾）