Definition of dinoflagellate
- a single-celled organism with two flagella, occurring in large numbers in marine plankton and also found in fresh water. Some produce toxins that can accumulate in shellfish, resulting in poisoning when eaten.
- Division Dinophyta or class Dinophyceae, division Chromophycota (or phylum Dinophyta, kingdom Protista)
late 19th century (as an adjective): from modern Latin Dinoflagellata (plural), from Greek dinos 'whirling' + Latin flagellum 'small whip' (see flagellum)