Source : Webster's Revised Unabridged Dictionary (1913)

Cnidaria \Cni*da"ri*a\, n. pl. [NL. See {Cnida}.] (Zo["o]l.)
   A comprehensive group equivalent to the true C[oe]lenterata,
   i. e., exclusive of the sponges. They are so named from
   presence of stinging cells (cnidae) in the tissues. See
   {Coelenterata}.

Source : WordNet®

Cnidaria
     n : hydras; polyps; jellyfishes; sea anemones; corals [syn: {phylum
         Cnidaria}, {Coelenterata}, {phylum Coelenterata}]