The Collaborative International Dictionary of English v.0.48:

Whirlpool \Whirl"pool`\, n.
   [1913 Webster]
   1. An eddy or vortex of water; a place in a body of water
      where the water moves round in a circle so as to produce a
      depression or cavity in the center, into which floating
      objects may be drawn; any body of water having a more or
      less circular motion caused by its flowing in an irregular
      channel, by the coming together of opposing currents, or
      the like.
      [1913 Webster]

   2. A sea monster of the whale kind. [Obs.] --Spenser.
      [1913 Webster]

            The Indian Sea breedeth the most and the biggest
            fishes that are; among which the whales and
            whirlpools, called "balaenae," take up in length as
            much as four . . . arpents of land.   --Holland.
      [1913 Webster]

WordNet (r) 3.0 (2006):

whirlpool
    n 1: a powerful circular current of water (usually the result of
         conflicting tides) [syn: whirlpool, vortex,
         maelstrom]
    v 1: flow in a circular current, of liquids [syn: eddy,
         purl, whirlpool, swirl, whirl]