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:
The researchers also noted that jellyfish, which diverged from humans about 600 to 700 million years ago, possess two nervous systems positioned at different ends of their bodies.
From Science Daily ● Sep. 21, 2026
He initially thought it was a compass jellyfish, which are native to UK waters, before realising it was too big.
From BBC ● Sep. 14, 2026
The Wildlife Trusts, external said the lion's mane jellyfish gets its name from its long tentacles, and have "all the beauty and bite of a lion".
From BBC ● Sep. 14, 2026
At first, postdoctoral researcher Olívia Soares Pereira thought the vehicle had come across a jellyfish.
From Los Angeles Times ● Sep. 5, 2026
A grandmotherly lady who studies jellyfish populations near Seattle.
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
When jellyfishes move, their tissue alternates between these states of tautness and gooeyness.
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
But the diminutive cousin in the grotto with the jellyfishes is a bird of quite another feather.
From A History of Science, Volume 5(of 5) Aspects Of Recent Science by Henry Smith Williams
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.
