資料來源 : Webster's Revised Unabridged Dictionary (1913)

Water wheel \Wa"ter wheel`\
   1. Any wheel for propelling machinery or for other purposes,
      that is made to rotate by the direct action of water; --
      called an {overshot wheel} when the water is applied at
      the top, an {undershot wheel} when at the bottom, a
      {breast wheel} when at an intermediate point; other forms
      are called {reaction wheel}, {vortex wheel}, {turbine
      wheel}, etc.

   2. The paddle wheel of a steam vessel.

   3. A wheel for raising water; a noria, or the like.

資料來源 : WordNet®

water wheel
     n 1: a wheel with buckets attached to its rim; raises water from
          a stream or pond [syn: {waterwheel}]
     2: a wheel that rotates by direct action of water; a simple
        turbine [syn: {waterwheel}]