di·​no·​fla·​gel·​late ˌdī-nō-ˈfla-jə-lət How to pronounce dinoflagellate (audio)
-flə-ˈje-lət How to pronounce dinoflagellate (audio)
: any of an order (Dinoflagellata) of chiefly marine planktonic usually solitary unicellular phytoflagellates that include luminescent forms, forms important in marine food chains, and forms causing red tide

Examples of dinoflagellate in a Sentence

Recent Examples on the Web Over the past week, 52 bloom concentration samples of the algae dinoflagellate Karenia brevis were detected from Southwest Florida, according to the FWC, which does water samples off the coast daily and updates its website several times a week. Garfield Hylton, orlandosentinel.com, 18 June 2021 In these photos, the blue glow is due to dinoflagellates, a type of algae, being disturbed in the water. Mark Graves | , oregonlive, 11 Aug. 2023 Bioluminescent Mosquito Bay is a traveler favorite as a classic Caribbean hideout during the day, and with the waters transforming by night, emitting a blue glow from the dinoflagellates organisms that live in the water. Brandon Presser, Harper's BAZAAR, 16 July 2023 See all Abstractions blog Researchers knew that certain classes of phytoplankton — diatoms, dinoflagellates and coccolithophores — stand out for their exceptional photosynthetic abilities. Kevin Hartnett, Quanta Magazine, 6 July 2023 The event is due to a chemical reaction that causes comb jellies (translucent sea creatures) and dinoflagellates (bioluminescent plankton) to emit blue light any time the water is disturbed. Talia Avakian, Travel + Leisure, 4 June 2023 Then, get to one of the three bioluminescent bays — Lajas, Fajardo, or Vieques — for a kayaking trip illuminated by glowing dinoflagellates. Chelsee Lowe, Travel + Leisure, 12 Apr. 2023 First described in 2009 in the unicellular green algae Micromonas, introners have subsequently turned up in the genomes of some other algae, some species of fungi, tiny marine organisms called dinoflagellates and simple invertebrates called tunicates. Jake Buehler, Quanta Magazine, 30 Mar. 2023 Most dinoflagellates are harmless, but some can produce neurotoxins that can cause respiratory problems in humans. Emily Deletter, The Enquirer, 6 Mar. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'dinoflagellate.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


borrowed from New Latin Dinoflagellatum, presumed singular of Dinoflagellata, order name, from dino- (in Dinophysis, Peridinium and the genus names of other protists having a second flagellum in a transverse groove; borrowed from Greek dīn-, in dīneîn "to whirl, spin about," dī́nē "whirlpool, eddy," dînos "whirling, rotation, eddy," probably originally a verbal base, of obscure origin) + Flagellata, former order name, from neuter plural of flagellātum flagellate entry 2

Note: The name was introduced in the 1880's by the German zoologist Otto Bütschli (1848-1920); in his paper "Einige Bemerkungen über gewisse Organisationsverhältnisse der sog. Cilioflagellaten und der Noctiluca," Morphologisches Jahrbuch, 10. Band (1885), pp. 529-77, Bütschli suggests the name as an alternative to Cilioflagellata, on the grounds that the girdle of cilia thought to characterize these protists is actually a flagellum fit inside a transverse groove: "In any case the need arises to exchange the name Cilioflagellata for another, as it rests on a really incorrect conception of its structure … I can also not recommend Stein's designation as the arthrodelous ['clearly jointed'] Flagellata, and I would hence like to propose the name Dinoflagellata, which at once calls to mind the earlier name Cilioflagellata in a certain respect, and then as well expresses the most characteristic peculiarities of the typical forms, that is, the formation of a transverse groove storing a flagellum." ("Jedenfalls wird sich aber die Nothwendigkeit ergeben, die Bezeichnung Cilioflagellaten mit einer anderen zu vertauschen, da sie auf einer tathsächlich unrichtigen Auffassung des Baues beruht … Mit Stein die Cilioflagellaten als arthrodele Flagellaten zu bezeichnen, halte ich auch nicht für empfehlenswerth und möchte daher vorschlagen, die Bezeichnung Dinoflagellata zu gebrauchen, welche einmal in gewisser Hinsicht an den früheren Namen Cilioflagellaten erinnert und dann die für die typischen Formen charakteristischste Eigenthümlichkeit, nämlich die Ausbildung der Querfurche mit der eingelagerten Geissel zum Ausdruck bringt.") Bütschli does not state explicitly why he chose dino-, though it most likely simply reflects the use of the form in genus names of protists possessing the second flagellum. The zoologist E. Ray Lankester, in the article on Protozoa for the ninth edition of the Encyclopaedia Britannica (1885), suggests in a discussion of Dinoflagellata that the allusion is to "Gr. dinos, the round area where oxen tread out on a threshing floor"—though this seems somewhat speculative and the relevance of dínos to a particular feature of the organism is not evident.

First Known Use

1901, in the meaning defined above

Time Traveler
The first known use of dinoflagellate was in 1901

Dictionary Entries Near dinoflagellate

Cite this Entry

“Dinoflagellate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/dinoflagellate. Accessed 11 Dec. 2023.

Kids Definition


: any of an order of chiefly marine single-celled floating organisms that resemble both algae and protozoa and are important in marine food chains

Medical Definition


di·​no·​fla·​gel·​late ˌdī-nō-ˈflaj-ə-lət How to pronounce dinoflagellate (audio) -ˌlāt How to pronounce dinoflagellate (audio)
: any of division or phylum (Dinoflagellata) of chiefly marine, planktonic, unicellular protists that include luminescent forms, forms important in marine food chains, and forms causing red tide

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