Source : Webster's Revised Unabridged Dictionary (1913)

Conch \Conch\, n. [L. concha, Gr. ?. See {Coach}, n.]
   1. (Zo["o]l.) A name applied to various marine univalve
      shells; esp. to those of the genus {Strombus}, which are
      of large size. {S. gigas} is the large pink West Indian
      conch. The large king, queen, and cameo conchs are of the
      genus {Cassis}. See {Cameo}.

   Note: The conch is sometimes used as a horn or trumpet, as in
         fogs at sea, or to call laborers from work.

   2. In works of art, the shell used by Tritons as a trumpet.

   3. One of the white natives of the Bahama Islands or one of
      their descendants in the Florida Keys; -- so called from
      the commonness of the conch there, or because they use it
      for food.

   4. (Arch.) See {Concha}, n.

   5. The external ear. See {Concha}, n., 2.

Source : WordNet®

conch
     n : any of various edible tropical marine gastropods of the
         genus Strombus having a brightly-colored spiral shell
         with large outer lip