Source : Webster's Revised Unabridged Dictionary (1913)

Starfish \Star"fish\, n.
   1. (Zo["o]l.) Any one of numerous species of echinoderms
      belonging to the class Asterioidea, in which the body is
      star-shaped and usually has five rays, though the number
      of rays varies from five to forty or more. The rays are
      often long, but are sometimes so short as to appear only
      as angles to the disklike body. Called also {sea star},
      {five-finger}, and {stellerid}.

   Note: The ophiuroids are also sometimes called starfishes.
         See {Brittle star}, and {Ophiuroidea}.

   2. (Zo["o]l.) The dollar fish, or butterfish.

Source : WordNet®

starfish
     n : echinoderms characterized by five arms extending from a
         central disk [syn: {sea star}]
     [also: {starfishes} (pl)]