Source : Webster's Revised Unabridged Dictionary (1913)

Aquatic \A*quat"ic\, a. [L. aquaticus: cf. F. aquatique. See
   {Aqua}.]
   Pertaining to water; growing in water; living in, swimming
   in, or frequenting the margins of waters; as, aquatic plants
   and fowls.

Aquatic \A*quat`ic\, n.
   1. An aquatic animal or plant.

   2. pl. Sports or exercises practiced in or on the water.

Source : WordNet®

aquatic
     adj 1: relating to or consisting of or being in water; "an aquatic
            environment"
     2: operating or living or growing in water; "boats are aquatic
        vehicles"; "water lilies are aquatic plants"; "fish are
        aquatic animals" [ant: {terrestrial}, {amphibious}]

aquatic
     n : a plant that lives in or on water