dinoflagellateEtymologyBorrowed from translingual Dinoflagellata (phylum name), equivalent to dino- + flagellate.nounAny of many marine protozoa of the phylum Dinoflagellata, which have two flagella.“Noctiluna scintillans, a tiny marine dinoflagellate, glows in the dark thanks to thousands of bioluminescent spherical organelles in its cytoplasm; gathered in millions, it can illuminate the whole sea at night.”