Pin, n.
 1. A piece of wood, metal, etc., generally cylindrical, used for fastening separate articles together, or as a support by which one article may be suspended from another; a peg; a bolt.
 With pins of adamant
 And chains they made all fast.   --Milton.
 2. Especially, a small, pointed and headed piece of brass or other wire (commonly tinned), largely used for fastening clothes, attaching papers, etc.
 3. Hence, a thing of small value; a trifle.
    He . . . did not care a pin for her.   --Spectator.
 4. That which resembles a pin in its form or use; as: (a) A peg in musical instruments, for increasing or relaxing the tension of the strings. (b) A linchpin. (c) A rolling-pin. (d) A clothespin. (e) Mach. A short shaft, sometimes forming a bolt, a part of which serves as a journal. See Illust. of Knuckle joint, under Knuckle. (f) Joinery The tenon of a dovetail joint.
 5. One of a row of pegs in the side of an ancient drinking cup to mark how much each man should drink.
 6. The bull's eye, or center, of a target; hence, the center. [Obs.] “The very pin of his heart cleft.”
 7. Mood; humor. [Obs.] “In merry pin.”
 8. Med. Caligo. See Caligo.
 9. An ornament, as a brooch or badge, fastened to the clothing by a pin; as, a Masonic pin.
 10. The leg; as, to knock one off his pins. [Slang]
 Banking pin Horol., a pin against which a lever strikes, to limit its motion.
 Pin drill Mech., a drill with a central pin or projection to enter a hole, for enlarging the hole, or for sinking a recess for the head of a bolt, etc.; a counterbore.
 Pin grass. Bot. See Alfilaria.
 Pin hole, a small hole made by a pin; hence, any very small aperture or perforation.
 Pin lock, a lock having a cylindrical bolt; a lock in which pins, arranged by the key, are used instead of tumblers.
 Pin money, an allowance of money, as that made by a husband to his wife, for private and personal expenditure.
 Pin rail Naut., a rail, usually within the bulwarks, to hold belaying pins. Sometimes applied to the fife rail. Called also pin rack.
 Pin wheel. (a) A contrate wheel in which the cogs are cylindrical pins. (b) Fireworks A small coil which revolves on a common pin and makes a wheel of yellow or colored fire.
 Fife n.  Mus. A small shrill pipe, resembling the piccolo flute, used chiefly to accompany the drum in military music.
 Fife major Mil., a noncommissioned officer who superintends the fifers of a regiment.
 Fife rail. Naut. (a) A rail about the mast, at the deck, to hold belaying pins, etc. (b) A railing around the break of a poop deck.
 fife rail
      n : the railing surrounding the mast of a sailing vessel