jellyfish
Americannoun
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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
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.
“You could tokenmaxx all day long but get outcomes that are not what you desired,” said Andrew Lau, co-founder and CEO of AI software engineering company Jellyfish.
From The Wall Street Journal • Apr. 14, 2026
Jellyfish galaxies get their name from the long, flowing streams of gas that stretch out behind them, resembling tentacles.
From Science Daily • Mar. 3, 2026
Jason Falkner, a former member of the great ’90s psych-pop band Jellyfish who’s played for years with Beck, filled in for Smear at the Forum, where Rubin’s kick drum bore a picture of Smear’s face.
From Los Angeles Times • Jan. 15, 2026
Green Jellyfish and Kirby and Haslam are both located at the Union Building on Rose Lane in Norwich.
From BBC • Sep. 25, 2024
Jellyfish when I opened them again and stared out into the blackness.
From "The Thing About Jellyfish" by Ali Benjamin
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.
