1 [count] : a thin, pointed piece of stiff wire with a rounded head at one end that is used especially for fastening pieces of cloth — see picture at sewing; see also bobby pin, clothespin, drawing pin, hairpin, safety pin 2 [count] a : a thin, pointed piece of stiff wire with a decoration at one end — see also hatpin
b chiefly US : brooch
c : a small usually circular object that has writing and often a picture on it and that has a pin on the back so that it can be fastened to clothing, bags, etc.
▪ He handed out pins with the peace sign on them. ▪ political campaign pins 3 [count] a : a thin piece of wood, metal, or plastic that is used for holding things together or for hanging one thing from another
b : a long, thin piece of metal that is used to fasten together the ends of broken bone 4 [count] Brit : one of the metal pieces that stick out from an electric plug and fit into a socket : prong
▪ a three-pin plug 5 [count] : a thin piece of metal that is removed to trigger the explosion of a small bomb (called a grenade)
▪ pull the pin 6 [count] golf : a long stick with a flag at the top that shows where the hole is on a green
▪ The ball landed near the pin. 7 [count] bowling : one of the usually white standing pieces that are knocked down with the ball — see also tenpin 8 pins [plural] informal : the legs of a person or animal
▪ They were knocked right off their pins by the heavy winds.