n. and order of plankton, in some classifications it is considered a phylum of the kingdom Protista; in others it is included in the plant phylum Pyrrophyta. Its members usually have two flagella, one of which extends from its center. Syn. -- order Dinoflagellata, Cilioflagellata, order Cilioflagellata. [ WordNet 1.5 +PJC ]
n. a member of the Dinoflagellata, chiefly marine protozoa having two flagella. The dinoflagellates form a chief constituent of plankton. [ WordNet 1.5 ]