pin

Multiple Entries:
  pin    PIN    personal identification number  

Concise Oxford English Dictionary © 2008 Oxford University Press:
pin/pɪn/

▶noun

• 1 a thin piece of metal with a sharp point at one end and a round head at the other, used for fastening pieces of cloth, paper, etc.

  ■ a small brooch or badge.

  ■ Medicine a steel rod used to join the ends of fractured bones while they heal.

• 2 a metal peg that holds down the activating lever of a hand grenade, preventing its explosion.

• 3 a metal projection from a plug or an integrated circuit which makes an electrical connection with a socket or another part of a circuit.

• 4 Golf a stick with a flag placed in a hole to mark its position.

• 5 a skittle in bowling.

• 6 (pins) informal legs.

• 7 Chess an attack on a piece or pawn which is thereby pinned.

• 8 Brit. historical a half-firkin cask for beer.

▶verb (pins, pinning, pinned)

• 1 attach or fasten with a pin or pins.

  ■ (pin something on) fix blame or responsibility on.

• 2 hold someone firmly so they are unable to move.

  ■ (pin someone down) restrict the actions of an enemy by firing at them.

  ■ (pin someone down) force someone to be specific about their intentions.

• 3 Chess hinder or prevent (a piece or pawn) from moving because of the danger to a more valuable piece standing behind it.

– phrases
pin one's ears back listen carefully.
pin one's hopes (or faith) on rely heavily on.

– origin OE pinn, of W. Gmc origin, from L. pinna ‘point, tip, edge’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
PIN /pɪn/ (also PIN number)

▶abbreviation personal identification number.

Concise Oxford English Dictionary © 2008 Oxford University Press:
personal identification number (abbrev.: PIN)

▶noun a number allocated to an individual and used to validate electronic transactions.