*dinoflagellata*

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 ]