jel·​ly·​fish | \ ˈje-lē-ˌfish How to pronounce jellyfish (audio) \

Definition of jellyfish

1a : 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)
2 : a person lacking backbone or firmness

Illustration of jellyfish

Illustration of jellyfish

jellyfish 1a

Synonyms & Antonyms for jellyfish



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Examples of jellyfish in a Sentence

a jellyfish who was afraid to tell her boss that her latest brainstorm was just plain bad
Recent Examples on the Web Ripley’s Aquarium of Canada Visit Ripley’s Aquarium of Canada’s sharks and jellyfish at a safe distance through live camera feeds. Sandra Macgregor, Forbes, 8 Apr. 2021 Many of the immune system’s players are transient molecules, and unearthing evidence of them now may prove nearly impossible — like trying to find a fossil of a jellyfish or a flatworm. Megan Molteni,, 15 Nov. 2021 But kites, even here, cannot turn into magical jellyfish that unclip from their line and fly, alive, into the woods. oregonlive, 18 Oct. 2021 Together, this means that the certain parts of the ocean are quickly becoming the jellyfish’s domain. Priya Shukla, Forbes, 13 Oct. 2021 While most often seen dead and flattened on beaches, in the water, the barrel jellyfish’s translucent bell takes on a mushroom shape, fringed with a brilliant violet ribbon of sensory organs. Alan Taylor, The Atlantic, 1 June 2021 But can your mind exist only in a biological substrate that weighs 1.5 kilograms, is very wet, and floats like a jellyfish? Margaret Talbot, The New Yorker, 11 Aug. 2021 Biomolecular tools that have worked for bacteria, jellyfish and algae for millions of years are now being used in medicine and biological research. Marc Zimmer, The Conversation, 5 Aug. 2021 Visitors can spend time with jellyfish and dolphins, or attend a half-price Friday night for an exciting kick off to the weekend. Maya Kachroo-levine, Travel + Leisure, 19 July 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'jellyfish.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of jellyfish

1818, in the meaning defined at sense 1a

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Time Traveler for jellyfish

Time Traveler

The first known use of jellyfish was in 1818

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Dictionary Entries Near jellyfish

jelly end rot


jelly fungus

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Statistics for jellyfish

Last Updated

30 Nov 2021

Cite this Entry

“Jellyfish.” Dictionary, Merriam-Webster, Accessed 1 Dec. 2021.

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More Definitions for jellyfish



English Language Learners Definition of jellyfish

: a sea animal that has a very soft body and that can sting


jel·​ly·​fish | \ ˈje-lē-ˌfish How to pronounce jellyfish (audio) \

Kids Definition of jellyfish

: a free-swimming sea animal related to the corals that has a nearly transparent jellylike body shaped like a saucer and tentacles with stinging cells


jel·​ly·​fish | \ ˈjel-ē-ˌfish How to pronounce jellyfish (audio) \

Medical Definition of jellyfish

: 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

More from Merriam-Webster on jellyfish

Nglish: Translation of jellyfish for Spanish Speakers Encyclopedia article about jellyfish


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