hairpin
n.a small, curved piece of metal or plastic used to hold your hair in place. It can also mean a very sharp turn in a road or a sudden change in a musical melody.
n.a small, curved fastener used to secure hair; by extension, a sharp bend in a road or a sudden change in musical pitch. Often used in the plural to describe a series of turns.
“She used a silver hairpin to keep her ponytail in place.”
“The narrow mountain road features a series of hairpins that require careful driving to navigate.”
“The composer's use of a sudden hairpin in the violin section created a dramatic contrast that silenced the entire audience for a moment.”
From hair + pin, 1788 (as hair pin). Adjective sense 1906 in hairpin turn etc.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.