Source : Webster's Revised Unabridged Dictionary (1913)

Waterspout \Wa"ter*spout`\, n.
   A remarkable meteorological phenomenon, of the nature of a
   tornado or whirlwind, usually observed over the sea, but
   sometimes over the land.

   Note: Tall columns, apparently of cloud, and reaching from
         the sea to the clouds, are seen moving along, often
         several at once, sometimes straight and vertical, at
         other times inclined and tortuous, but always in rapid
         rotation. At their bases, the sea is violently agitated
         and heaped up with a leaping or boiling motion, water,
         at least in some cases, being actually carried up in
         considerable quantity, and scattered round from a great
         height, as solid bodies are by tornadoes on land. --Sir
         J. Herschel.

Source : WordNet®

waterspout
     n 1: a tornado passing over water and picking up a column of
          water and mist
     2: a heavy rain [syn: {downpour}, {cloudburst}, {deluge}, {torrent},
         {pelter}, {soaker}]
     3: a channel through which water is discharged (especially one
        used for drainage from the gutters of a roof)