A bobby pin is a small piece of metal or plastic bent back on itself, which someone uses to hold their hair in position. A small metal hair clip with the ends pressed tightly together. a thin piece of metal bent into a narrow U shape that you use to hold your hair in place British Equivalent: hairgrip (Probably from BOB1)
a flat wire hairpin whose prongs press tightly together; used to hold bobbed hair in place; "in England they call a bobby pin a grip