The Collaborative International Dictionary of English v.0.48:

Swivel \Swiv"el\, n. [AS. sw[imac]fan to move quickly, to
   remove; akin to Icel. sveifla to whirl, shake, sv[imac]fa to
   ramble, to turn. See Swoop, and cf. Swift a reel,
   Swift, a.]
   1. (Mech.) A piece, as a ring or hook, attached to another
      piece by a pin, in such a manner as to permit rotation
      about the pin as an axis.
      [1913 Webster]

   2. (Mil.) A small piece of ordnance, turning on a point or
      swivel; -- called also swivel gun. --Wilhelm.
      [1913 Webster]

   Swivel bridge, a kind of drawbridge that turns round on a
      vertical axis; a swing bridge.

   Swivel hook, a hook connected with the iron strap of a
      pulley block by a swivel joint, for readily taking the
      turns out of a tackle.

   Swivel joint, a joint, the two pieces composing which turn
      round, with respect to each other, on a longitudinal pin
      or axis, as in a chain, to prevent twisting.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Swivel \Swiv"el\, v. i.
   To swing or turn, as on a pin or pivot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

swivel
    n 1: a coupling (as in a chain) that has one end that turns on a
         headed pin
    v 1: turn on a pivot [syn: pivot, swivel]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "swivel":
   arbor, axis, axle, axle bar, axle shaft, axle spindle, axle-tree,
   circle, circulate, circumrotate, circumvolute, come about, crank,
   distaff, fetch about, fulcrum, gimbal, go about, go around,
   go round, gudgeon, gyrate, gyre, heel, hinge, hingle, hub, mandrel,
   nave, oarlock, pin, pintle, pirouette, pivot, pivot about, pole,
   put about, radiant, revolve, rotate, round, rowlock, screw, spin,
   spindle, swing, swing round, trunnion, turn, turn a pirouette,
   turn about, turn around, turn round, turn tail, twist, veer,
   veer around, wamble, wheel, wheel about, whirl, wind