jellyfish

noun

jel·ly·fish ˈje-lē-ˌfish

: the typically free-swimming, bell-shaped, usually sexually-reproducing solitary or colonial form of a cnidarian in which the whorls of tentacles lined with nematocysts arise and hang down from the margin of the nearly transparent, gelatinous bell : medusa

especially : a large medusa characteristic of the siphonophores and scyphozoans (such as the sea nettle or box jellyfish)

: siphonophore

: ctenophore

: a person lacking backbone or firmness

Example Sentences

a jellyfish who was afraid to tell her boss that her latest brainstorm was just plain bad

Recent Examples on the Web From this wealth of genomic data, the team discovered four fusion-and-mixing events shared by bilaterians (amphioxus), jellyfish, and sponges but not by ctenophores. —

Viviane Callier, Scientific American, 17 May 2023 The Tully monster, however, has few of such parts—not unlike jellyfish and worms, which lack hard skeletal structures and leave only impressions in sediment as they are fossilized. —

Jamie Dickman, Popular Science, 17 Apr. 2023 By-the-wind sailors are related to jellyfish and the Portuguese man-of-war, which can produce a painful sting, but their tentacles are mostly harmless, Pernet said. —

Salvador Hernandez, Los Angeles Times, 10 Apr. 2023 Cut into squiggly tendrils—not unlike strands of noodle—the jellyfish is traditionally tossed in a simple vinaigrette of soy sauce and rice vinegar. —

Jenny Liao, Bon Appétit, 23 Feb. 2023 The jellyfish showed no signs of stress or other adverse effects after being released, and the fingers were able to open and close roughly 100 times before showing signs of wear and tear. —

IEEE Spectrum, 23 Jan. 2023 The animal is the polyp, a transparent, tentacled creature related to anemone and jellyfish. —

Michael Robinson Chavez, Washington Post, 22 Nov. 2022 Chubby fish in blue water created by the younger students transition to a scene by a fifth-grader featuring a seahorse, crab, jellyfish and aquatic plant life on a sandy ocean bottom. —

Mary Jane Brewer, cleveland, 20 Nov. 2022 Before that, researchers captured footage of a rare jellyfish for the first time. —

Joshua Hawkins, BGR, 19 Oct. 2022 See More

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

Word History

First Known Use

1818, in the meaning defined at sense 1a

Time Traveler

The first known use of jellyfish was in 1818

See more words from the same year

Cite this Entry

Style

“Jellyfish.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/jellyfish. Accessed 30 May. 2023.

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Kids Definition

jellyfish

noun

jel·ly·fish ˈjel-ē-ˌfish

: any of numerous free-swimming coelenterate animals that reproduce sexually and have a jellylike, saucer-shaped, and usually nearly transparent body and tentacles with stinging cells

: any of various sea animals that resemble a jellyfish

Medical Definition

jellyfish

noun

jel·ly·fish ˈjel-ē-ˌfish

: a free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells