jellyfish

noun

jel·ly·fish | \ ˈje-lē-ˌfish

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)

b : siphonophore

c : ctenophore

2 : a person lacking backbone or firmness

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Synonyms & Antonyms for jellyfish

Synonyms

doormat, namby-pamby, pushover, reed, weakling, wimp

Antonyms

stalwart

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

His central discovery was centered on a North American jellyfish, Aequorea victoria, sometimes called the crystal jelly. — Harrison Smith, The Seattle Times, "Osamu Shimomura, atomic blast survivor and Nobel-winning chemist, dies at 90," 23 Oct. 2018 Among those species was a giant, tentacle-less jellyfish, which eventually came to be known as Deepstaria enigmatica. — National Geographic, "This Mysterious Deep-Sea Jellyfish Looks Like a Plastic Bag," 14 May 2018 The meager calories in jellyfish weren’t the only reason that scientists dismissed them. — Carl Zimmer, The Seattle Times, "In the sea, a big appetite for jellyfish," 26 Oct. 2018 While working at Friday Harbor Laboratories, a field station run by the University of Washington, Shimomura discovered a jellyfish protein that allows scientists to trace the movement of cells and proteins. — Seattle Times Staff & News Services, The Seattle Times, "This week’s passages," 26 Oct. 2018 Opt for a wetsuit over a traditional bathing suit to stay relatively warmer into September and more protected from the sun, surfboard rash, and even jellyfish. — Mara Balagtas, Condé Nast Traveler, "Our 10 Favorite Wetsuits for the Dog Days of Summer," 9 Aug. 2018 Now the Arctic is a warm body, full of jellyfish and black chokeweed. — Smith Henderson, Popular Mechanics, "Olympia," 20 Nov. 2017 According to a study done last year, jellyfish might be older, but that study used genetic analysis and not fossilized evidence. — Chris Ciaccia, Fox News, "'Holy Grail' fossil mystery cracked – 558 million-year-old fat reveals earliest known animal," 21 Sep. 2018 Dangling from the brain like the tentacles of a jellyfish, olfactory neurons are the only part of the central nervous system constantly exposed to the outside world. — Tim Folger, Discover Magazine, "How Quantum Mechanics Lets Us See, Smell and Touch," 24 Oct. 2018

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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Statistics for jellyfish

Last Updated

17 Mar 2019

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Time Traveler for jellyfish

The first known use of jellyfish was in 1818

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More Definitions for jellyfish

jellyfish

noun

English Language Learners Definition of jellyfish

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

See the full definition for jellyfish in the English Language Learners Dictionary

jellyfish

noun

jel·ly·fish | \ ˈje-lē-ˌfish

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

jellyfish

noun

jel·ly·fish | \ ˈjel-ē-ˌfish

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