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

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 whale’s gullet is flickeringly lit by a bioluminescent jellyfish that Jay sort of befriends.

From Los Angeles Times ● Oct. 15, 2026

The most important thing to know about prehistoric humans is that they were insignificant animals with no more impact on their environment than gorillas, fireflies or jellyfish.

From "Sapiens: A Brief History of Humankind" by Yuval Noah Harari

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

A group of acalephs, including most of the larger jellyfishes; the Discophora.

From Webster's Unabridged Dictionary by Noah Webster

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