The Collaborative International Dictionary of English v.0.48:

Pin \Pin\, v. t. (Metal Working)
   To peen.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pin \Pin\, v. t. [Cf. Pen to confine, or Pinfold.]
   To inclose; to confine; to pen; to pound.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pin \Pin\, n. [OE. pinne, AS. pinn a pin, peg; cf. D. pin, G.
   pinne, Icel. pinni, W. pin, Gael. & Ir. pinne; all fr. L.
   pinna a pinnacle, pin, feather, perhaps orig. a different
   word from pinna feather. Cf. Fin of a fish, Pen a
   feather.]
   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.
      [1913 Webster]

            With pins of adamant
            And chains they made all fast.        --Milton.
      [1913 Webster]

   2. Especially, a small, pointed and headed piece of brass or
      other wire (commonly tinned), largely used for fastening
      clothes, attaching papers, etc.
      [1913 Webster]

   3. Hence, a thing of small value; a trifle.
      [1913 Webster]

            He . . . did not care a pin for her.  --Spectator.
      [1913 Webster]

   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.
          [1913 Webster]

   5. One of a row of pegs in the side of an ancient drinking
      cup to mark how much each man should drink.
      [1913 Webster]

   6. The bull's eye, or center, of a target; hence, the center.
      [Obs.] "The very pin of his heart cleft." --Shak.
      [1913 Webster]

   7. Mood; humor. [Obs.] "In merry pin." --Cowper.
      [1913 Webster]

   8. (Med.) Caligo. See Caligo. --Shak.
      [1913 Webster]

   9. An ornament, as a brooch or badge, fastened to the
      clothing by a pin; as, a Masonic pin.
      [1913 Webster]

   10. The leg; as, to knock one off his pins. [Slang]
       [1913 Webster]

   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.
           [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pin \Pin\, v. t. [imp. & p. p. Pinned; p. pr. & vb. n.
   Pinning.] [See Pin, n.]
   To fasten with, or as with, a pin; to join; as, to pin a
   garment; to pin boards together. "As if she would pin her to
   her heart." --Shak.
   [1913 Webster]

   To pin one's faith upon, to depend upon; to trust to.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pin
    n 1: a piece of jewelry that is pinned onto the wearer's garment
    2: when a wrestler's shoulders are forced to the mat [syn:
       fall, pin]
    3: small markers inserted into a surface to mark scores or
       define locations etc. [syn: peg, pin]
    4: a number you choose and use to gain access to various
       accounts [syn: personal identification number, PIN, PIN
       number]
    5: informal terms for the leg; "fever left him weak on his
       sticks" [syn: pin, peg, stick]
    6: axis consisting of a short shaft that supports something that
       turns [syn: pivot, pin]
    7: cylindrical tumblers consisting of two parts that are held in
       place by springs; when they are aligned with a key the bolt
       can be thrown [syn: pin, pin tumbler]
    8: flagpole used to mark the position of the hole on a golf
       green [syn: pin, flag]
    9: a small slender (often pointed) piece of wood or metal used
       to support or fasten or attach things
    10: a holder attached to the gunwale of a boat that holds the
        oar in place and acts as a fulcrum for rowing [syn: peg,
        pin, thole, tholepin, rowlock, oarlock]
    11: a club-shaped wooden object used in bowling; set up in
        triangular groups of ten as the target [syn: bowling pin,
        pin]
    v 1: to hold fast or prevent from moving; "The child was pinned
         under the fallen tree" [syn: trap, pin, immobilize,
         immobilise]
    2: attach or fasten with pins or as if with pins; "pin the
       needle to the shirt". "pin the blame on the innocent man"
       [ant: unpin]
    3: pierce with a pin; "pin down the butterfly"
    4: immobilize a piece

The Free On-line Dictionary of Computing (19 January 2023):

Personal Identification Number
PIN

    (PIN, "PIN number") A password, typically four
   digits entered through a telephone keypad or automatic teller
   machine.

   (1996-11-03)