Hairpin can mean:* A long device used to hold a person's hair in place: see below Hairpin bend A stem-loop in biochemistry. A hair pin or hairpin is a long device used to hold a person's hair in place. Hairpins made of metal, ivory, bronze, carved wood, etc. were used in ancient Assyria and Egypt for securing decorated hairstyles. Such hairpins suggest, as graves show, that many were luxury objects among the Egyptians and later Greeks, Etruscans, and Romans. Major success came in 1901 with t… (More on Hairpin)