jellyfish
Americannoun
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jellyfish,
plural
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jellyfishes
plural
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any of various marine coelenterates of a soft, gelatinous structure, especially one with an umbrellalike body and long, trailing tentacles; medusa.
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Informal. a person without strong resolve or stamina; an indecisive or weak person.
noun
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any marine medusoid coelenterate of the class Scyphozoa, having a gelatinous umbrella-shaped body with trailing tentacles
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any other medusoid coelenterate
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informal a weak indecisive person
Other Word Forms
Noun Inflected Forms
Etymology
Origin of jellyfish
1700–10; 1910–15 jellyfish for def. 2; jelly + fish
Explanation
A jellyfish is a marine animal with long tentacles that hang down from a bell-shaped body. Many jellyfish are nearly transparent. Jellyfish may look like they're made of jelly, but their bodies are actually 95 percent water. These umbrella-shaped creatures look graceful floating in the water, but they collapse into a flat blob on land. Jellyfish don't have organs, just a simple nervous system and three layers including the elastic, jelly-like mesoglea that gives them their name. In the 19th century, it became fairly common to call a weak person a jellyfish, a figurative usage that's still around today.
Vocabulary lists containing jellyfish
Reef Awareness Day, List 1
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Marine Biology - Introductory
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Marine Biology - Middle School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
At first, postdoctoral researcher Olívia Soares Pereira thought the vehicle had come across a jellyfish.
From Los Angeles Times ● Sep. 5, 2026
A massive influx of jellyfish has led to the partial shutdown of a nuclear reactor in northern France.
From BBC ● Aug. 27, 2026
Hot weather increases plankton levels at the water's surface, drawing jellyfish up, experts say.
From BBC ● Aug. 27, 2026
A collaged print by Liu Shiyuan presents a dizzying array of images—fruit, bees, jellyfish, shrouded figures, fabric samples—that is more disorienting than anything else.
From The Wall Street Journal ● Aug. 21, 2026
Since then she developed the first-ever treatment for a jellyfish sting.
From "The Thing About Jellyfish" by Ali Benjamin
These showed body plans different from any animals alive today, although some seem to be related to worms and jellyfishes.
From Textbooks ● Jan. 1, 2018
“We need to clearly acknowledge that jellyfishes and other gelatinous organisms may be a regular prey for a variety of marine predators.”
From National Geographic ● Sep. 15, 2017
Both squishy and elastic, jellyfishes can snap like a rubber band over a short periods of time span and ooze like goo over longer periods.
From Scientific American ● Jun. 24, 2015
Expect giraffes and zebras, but also Komodo dragons, jellyfishes and newts for a dash of originality.
From The Guardian ● Feb. 1, 2013
There are of course a great number of animals—such as jellyfishes, and other animals—without any hard parts, of which we cannot reasonably expect to find any traces whatever: there is nothing of them to preserve.
From Darwiniana : Essays — Volume 02 by Thomas Henry Huxley
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
