Hairpin can mean:
- Hairpin (fashion), a long device used to hold a person's hair in place
- Hairpin turn, tight turns on a road
- Hairpin cotter, a formed wire fastener most commonly used in clevis pins
- Hairpin clip, a formed wire fastener designed for use in grooved shafts
- A stem-loop in biochemistry
- β-Hairpin, a secondary structure motif of proteins
- Hairpins (film), a 1920 film directed by Fred Niblo
- Hairpin, in music, the nickname for crescendo and decrescendo markings. See Dynamics (music)#Gradual changes