flagellum

American  

[fluh-jel-uhm] / fləˈdʒɛl əm /

noun

plural

flagella, flagellums

1. Biology. a long, lashlike appendage serving as an organ of locomotion in protozoa, sperm cells, etc.

2. Botany. a runner.

3. Also called clavola.  Entomology. (in an antenna) the whiplike portion above the basal joints.

4. a whip or lash.

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flagellum British  

/ fləˈdʒɛləm /

noun

1. biology a long whiplike outgrowth from a cell that acts as an organ of locomotion: occurs in some protozoans, gametes, spores, etc

2. botany a long thin supple shoot or runner

3. zoology the terminal whiplike part of an arthropod's appendage, esp of the antenna of many insects

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flagellum Scientific  

/ flə-jĕl′əm /

plural

flagella

1. A slender whiplike part extending from some single-celled organisms, such as the dinoflagellates, that moves rapidly back and forth to impart movement to the organism.

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Other Word Forms

• flagellar adjective

Etymology

Origin of flagellum

1800–10; < Latin: whip, lash, diminutive of flagrum a whip, scourge

Explanation

A flagellum is part of a cell, a sort of thread that helps the cell move around by moving like a whip. Bacteria are among the cells that can have flagella. In a bacterial cell, a flagellum twists in a circle like a screw, while in a eukaryote (a plant or animal cell), the flagellum moves in more of an S motion. These long, lash-like appendages propel cells forward, but they also help them sense temperature changes and the presence of certain chemicals. In Latin, flagellum means "whip," from a Proto-Indo-European root meaning "to strike."

Example Sentences

The flagellum comprises more than 30 distinct parts, so similar to those of an outboard motor that biologists speak of the flagellum’s propeller, drive shaft and so forth.

From The Wall Street Journal • Apr. 16, 2026

Some of the most revealing genetic losses involved genes responsible for forming the tail, or flagellum, of sperm.

From Science Daily • Jan. 31, 2026

All five isolates exhibited a distinctive feature of Minorisa, a single flagellum coiled spirally around the cell.

From Science Daily • Oct. 26, 2023

Within 24 hours, the fungus can produce thousands more spores that are released back into the water, where they swim using a threadlike structure called a flagellum.

From Washington Post • Mar. 15, 2023

It bore a long flagellum at the end furthest from its point of attachment, the method of which I could not ascertain.

From Freshwater Sponges, Hydroids & Polyzoa by Annandale, Nelson