swiv·el /ˈswɪvəl/
  轉環,旋轉軸承,旋轉椅的臺座(vt.)(vi.)(使)旋轉
  Swiv·el n.
  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.
  2. Mil. A small piece of ordnance, turning on a point or swivel; -- called also swivel gun.
  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.
  Swiv·el, v. i. To swing or turn, as on a pin or pivot.
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  swivel
       n : a coupling (as in a chain) that has one end that turns on a
           headed pin
       v : turn on a pivot [syn: pivot]
       [also: swivelling, swivelled]