The Collaborative International Dictionary of English v.0.48:

Spindle \Spin"dle\, n. [AS. spinal, fr. spinnan to spin; akin to
   D. spil, G. spille, spindel, OHG. spinnala. [root]170. See
   Spin.]
   1. The long, round, slender rod or pin in spinning wheels by
      which the thread is twisted, and on which, when twisted,
      it is wound; also, the pin on which the bobbin is held in
      a spinning machine, or in the shuttle of a loom.
      [1913 Webster]

   2. A slender rod or pin on which anything turns; an axis; as,
      the spindle of a vane. Specifically:
      [1913 Webster]
      (a) (Mach.) The shaft, mandrel, or arbor, in a machine
          tool, as a lathe or drilling machine, etc., which
          causes the work to revolve, or carries a tool or
          center, etc.
          [1913 Webster]
      (b) (Mach.) The vertical rod on which the runner of a
          grinding mill turns.
          [1913 Webster]
      (c) (Founding) A shaft or pipe on which a core of sand is
          formed.
          [1913 Webster]

   3. The fusee of a watch.
      [1913 Webster]

   4. A long and slender stalk resembling a spindle.
      [1913 Webster]

   5. A yarn measure containing, in cotton yarn, 15,120 yards;
      in linen yarn, 14,400 yards.
      [1913 Webster]

   6. (Geom.) A solid generated by the revolution of a curved
      line about its base or double ordinate or chord.
      [1913 Webster]

   7. (Zool.)
      (a) Any marine univalve shell of the genus Rostellaria;
          -- called also spindle stromb.
      (b) Any marine gastropod of the genus Fusus.
          [1913 Webster]

   Dead spindle (Mach.), a spindle in a machine tool that does
      not revolve; the spindle of the tailstock of a lathe.

   Live spindle (Mach.), the revolving spindle of a machine
      tool; the spindle of the headstock of a turning lathe.

   Spindle shell. (Zool.) See Spindle, 7. above.

   Spindle side, the female side in descent; in the female
      line; opposed to spear side. --Ld. Lytton. [R.] "King
      Lycaon, grandson, by the spindle side, of Oceanus."
      --Lowell.

   Spindle tree (Bot.), any shrub or tree of the genus
      Eunymus. The wood of Eunymus Europaeus was used for
      spindles and skewers. See Prickwood.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spindle \Spin"dle\, v. i. [imp. & p. p. Spindled; p. pr. & vb.
   n. Spindling.]
   To shoot or grow into a long, slender stalk or body; to
   become disproportionately tall and slender.
   [1913 Webster]

         It has begun to spindle into overintellectuality.
                                                  --Lowell.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spindle
    n 1: (biology) tiny fibers that are seen in cell division; the
         fibers radiate from two poles and meet at the equator in
         the middle; "chromosomes are distributed by spindles in
         mitosis and meiosis"
    2: a piece of wood that has been turned on a lathe; used as a
       baluster, chair leg, etc.
    3: any of various rotating shafts that serve as axes for larger
       rotating parts [syn: spindle, mandrel, mandril,
       arbor]
    4: a stick or pin used to twist the yarn in spinning
    5: any holding device consisting of a rigid, sharp-pointed
       object; "the spike pierced the receipts and held them in
       order" [syn: spike, spindle]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "spindle":
   arbor, axis, axle, axle bar, axle shaft, axle spindle, axle-tree,
   distaff, fulcrum, gimbal, gudgeon, hinge, hingle, hub, mandrel,
   nave, oarlock, pin, pintle, pivot, pole, radiant, rowlock, swivel,
   trunnion