jellyfish

American  

[jel-ee-fish] / ˈdʒɛl iˌfɪʃ /

noun

• jellyfish,
  plural
• jellyfishes
  plural

1. any of various marine coelenterates of a soft, gelatinous structure, especially one with an umbrellalike body and long, trailing tentacles; medusa.

2. Informal. a person without strong resolve or stamina; an indecisive or weak person.

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jellyfish British  

/ ˈdʒɛlɪˌfɪʃ /

noun

1. any marine medusoid coelenterate of the class Scyphozoa, having a gelatinous umbrella-shaped body with trailing tentacles

2. any other medusoid coelenterate

3. informal a weak indecisive person

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Other Word Forms

Noun Inflected Forms

• jellyfish
  plural
• jellyfishes
  plural

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.

Example Sentences

See Examples For:

jellyfish jellyfishes

At first, postdoctoral researcher Olívia Soares Pereira thought the vehicle had come across a jellyfish.

From Los Angeles Times ● Sep. 5, 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

Swarms of jellyfish have also forced nuclear plants to shut down elsewhere, including a three-day closure in Sweden in 2013 and a 1999 incident in Japan that caused a major drop in output.

From Barron's ● Aug. 11, 2026

Then the heat sinks heavily into our shell-holes like a jellyfish, moist and oppressive and on one of these late summer days, while bringing food, Kat falls.

From "All Quiet on the Western Front: A Novel" by Erich Maria Remarque

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

Nothing can be prettier than the smaller kinds of jellyfishes.

From Louis Agassiz: His Life and Correspondence by Louis Agassiz

Related Words

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• crybaby
• pushover