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

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Etymology

Origin of jellyfish

1700–10; 1910–15 jellyfish for def. 2; jelly + fish

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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

Mr. Firestein mentions research on a species of jellyfish that led to the unexpected discovery of a new protein now “used to uncover genes expressed in cancer cells.”

From The Wall Street Journal ● Oct. 23, 2026

In the end, the jellyfish didn’t pose any issues, though she said she did have some “very magical” encounters with dolphins and sea lions.

From Los Angeles Times ● Oct. 21, 2026

As the rocket climbed above Earth carrying a Dragon spacecraft, sunlight illuminated its expanding exhaust plumes, creating an enormous glowing shape that resembled a jellyfish.

From Science Daily ● Oct. 18, 2026

The Bluebottle drone, manufactured in Sydney, is named after a small jellyfish with a painful sting that washes ashore on Australian beaches.

From Barron's ● Oct. 16, 2026

The jellyfish is in the top of the tank, and you beneath it, looking up.

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

The Cambrian period was the time of the establishment of the chief stocks of backboneless animals such as sponges, jellyfishes, worms, sea-cucumbers, lamp-shells, trilobites, crustaceans, and molluscs.

From The Outline of Science, Vol. 1 (of 4) A Plain Story Simply Told by J. Arthur Thomson

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