Cnidaria /(nĭ*dā"rĭ*ȧ)/

Cni·da·ri·a

Cnidaria

n. pl.
  1. A comprehensive group equivalent to the true Cœlenterata, i. e., exclusive of the sponges. They are so named from presence of stinging cells (cnidae) in the tissues. See Coelenterata. (Zool.)