pin / pin/ • n. 1. a small piece of metal or wood for fastening or attaching things, in particular: ∎  a thin piece of metal with a sharp point at one end and a round head at the other, used esp. for fastening pieces of cloth. ∎  a small brooch or badge. ∎  Med. a steel rod used to join the ends of fractured bones while they heal. ∎  a metal peg that holds down the activating lever of a hand grenade, preventing its explosion. ∎ short for hairpin. ∎ Mus. a peg around which one string of a musical instrument is fastened.2. a short piece of wood or metal for various purposes, in particular: ∎  (in bowling) one of a set of bottle-shaped wooden pieces that are arranged in an upright position at the end of a lane in order to be toppled by a rolling ball. ∎  a metal projection from a plug or an integrated circuit that makes an electrical connection with a socket or another part of a circuit. ∎ Golf a stick with a flag placed in a hole to mark the hole’s position.3. (pins) inf. legs: she was very nimble on her pins.4. Chess an attack on a piece or pawn, which is thereby pinned: the pin of the black queen by the white rook.• v. (pinned, pin·ning) [tr.] attach with a pin or pins: pin a note on the door. ∎  fasten (something) with a pin or pins in a specified position: her hair was pinned back. ∎  (pin something on) fix blame or responsibility for something on (someone): don’t pin the blame on me. ∎  hold someone firmly in a specified position so they are unable to move: she was standing pinned against the door. ∎  [tr.] transfix (something) with a pin or other pointed instrument: carefully pin the preserved insect specimens to the display surface. ∎  [tr.] Chess hinder or prevent (a piece or pawn) from moving because of the danger to a more valuable piece standing behind it along the line of an attack.PHRASES: (as) neat (or clean) as a pin extremely neat or clean.hear a pin drop used to describe absolute silence.on pins and needles in an agitated state of suspense.pin one's ears back listen carefully.pin one's hopes (or faith) on rely heavily on: retailers were pinning their hopes on a big-spending Christmas.PHRASAL VERBS: pin someone down restrict the actions or movement of an enemy by firing at them. ∎  force someone to be specific and make their intentions clear.pin something down define something precisely.