n. plCnidarianĭ*dā"rĭ*ȧ(Zoöl) 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.
Century Dictionary and Cyclopedia
cnidariaThose Cœlentera which have thread-cells or cnidœ; the Cœlenterata, with the exception of the sponges. See Cœlentera.
Webster's Revised Unabridged Dictionary
NL. See Cnida
Next in order come the tentacles, common to all Cnidaria.
"Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 2" by Various