<p><strong>Noun:</strong></p><ul><li>Any invertebrate animal, as a hydra, jellyfish, sea anemone, or coral, considered as belonging to the phylum Cnidaria, characterized by the specialized stinging structures in the tentacles surrounding the mouth; a coelenterate.</li></ul><p><strong>Adjective:</strong></p><ul><li>Belonging or pertaining to the Cnidaria.</li></ul>