noun. A marine invertebrate belonging to the now obsolete phylum Coelenterata, which included the cnidarians and sometimes also the ctenophores.

noun. Any simple aquatic animal bearing tentacles with nematocysts. Examples include jellyfish, coral, and anemones.

noun. radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms

"Cnidaria and Ctenophora are now classified as separate phyla, and the term "coelenterate" sent off to the rubbish heap of obsolete biological terms."

invertebrate  

Medusa  actinozoan  anthozoan  hydroid  hydrozoan  

cnidarian