1. noun /pɪn/
a) A small device, made (usually) of drawn-out steel wire with one end sharpened and the other flattened or rounded into a head, used for fastening.
Im not so good on my pins these days.
The UK standard connector for domestic mains electricity has three pins.
2. verb /pɪn/
a) (often followed by a preposition such as to or on) To fasten or attach (something) with a pin. <!this is "pin on" to attribute blame
...you cant pin that robbery on me!
b) To cause (a piece) to be in a pin.
Wikipedia foundation.