1With plural (or occasionally singular) agreement: a phylum or group of aquatic acoelomate invertebrates comprising the members of the present-day phyla Cnidaria and (in earlier use) Ctenophora. Also with plural agreement: animals of this phylum (collectively or individually); coelenterates.
The Cnidaria and Ctenophora are now known to be only superficially similar, having jelly-like bodies and stinging tentacles. The name Coelenterata has effectively been replaced by Cnidaria.
2historical With plural agreement. A major subdivision of the Metazoa, distinguished from the Coelomata by having an intestinal canal but no body cavity or coelom, and comprising the Porifera (sponges) as well as the Cnidaria and Ctenophora.
Mid 19th century; earliest use found in Jabez Hogg (1817–1899), ophthalmic surgeon. From scientific Latin Coelenterata from ancient Greek κοῖλος hollow + ἔντερον + scientific Latin -ata.