jellyfish

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noun jel·ly·fish \ ˈje-lē-ˌfish \

Definition of jellyfish

1 a :a free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells

b :siphonophore

c :ctenophore

2 :a person lacking backbone or firmness

See jellyfish defined for English-language learners

See jellyfish defined for kids

Examples of jellyfish in a Sentence

a jellyfish who was afraid to tell her boss that her latest brainstorm was just plain bad

Recent Examples of jellyfish from the Web

The jellyfish pulsate at a hypnotic pace, offering a quick remedy for travel stress at one of two on-site Vancouver Aquarium exhibits containing more than 5,000 sea creatures at this Canadian airport.

— kate silver, chicagotribune.com, "Butterfly garden and golf? 9 airports with insane amenities," 18 Aug. 2017
Toth said the aquarium has also worked information about plastic waste into its regular exhibits and has one exhibit that shows floating plastic bags and jellyfish side by side.

— jennifer larino, NOLA.com, "Here's why the Audubon Aquarium has stopped offering plastic straws," 11 July 2017
Blatnica, who teaches at Berea-Midpark High School, used his grant for a science experiment in which students transferred DNA from one luminescent animal (a jellyfish) to a non-luminescent organism (bacteria).

— rich heileman, cleveland.com, "BW's bookstore offers spruced-up computers at low cost: Around The Town," 7 July 2017
The jellyfish have come through the Suez Canal, which was first built in 1869.

— menna zaki, The Seattle Times, "Jellyfish invasion stirs debate over Egypt’s Suez Canal," 6 July 2017
The video from his April 17 dive revealed vibrant sea creatures that have made the chilly northern waters their home—among them, a transparent Arctic jellyfish, a sparkly skeleton shrimp, and a white nudibranch, or soft-bodied mollusk.

— hannah lang, National Geographic, "A Thriving Ecosystem Is Hiding Underneath Greenland’s Ice Caps," 6 July 2017
Sea lice Irritating rash is seldom harmful Sea lice are not insects but baby thimble jellyfish.

— bonnie berkowitz, chicagotribune.com, "10 creatures that can ruin your day at the beach," 30 June 2017
In this video, shot by marine biologist Johnny Gaskell, a young green sea turtle munches on a jellyfish in the shallow waters around Hook Island, Queensland, in Australia’s famous Great Barrier Reef.

— rachel brown, National Geographic, "Watch: Sea Turtle Snacks on Jellyfish Tentacles," 27 June 2017
Most of the Gulf is a barren desert, empty sand and little else but jellyfish and starfish.

— AL.com, "Alabama's 60,000-year-old underwater forest spills its secrets in new documentary," 25 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'jellyfish.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Illustration of jellyfish

First Known Use of jellyfish

1841

jellyfish Synonyms

Synonyms

doormat, weakling, namby-pamby, pushover, reed, wimp

Antonyms

stalwart

Related Words

coward, milquetoast, mouse, nebbish, nervous Nellie (or nervous Nelly), pussy [slang], wuss (also wussy); sheep

Near Antonyms

mensch

JELLYFISH Defined for English Language Learners

jellyfish

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noun

Definition of jellyfish for English Language Learners

: a sea animal that has a very soft body and that can sting

JELLYFISH Defined for Kids

jellyfish

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noun jel·ly·fish \ ˈje-lē-ˌfish \

Definition of jellyfish for Students

:a free-swimming sea animal related to the corals that has a nearly transparent jellylike body shaped like a saucer and tentacles with stinging cells

Medical Dictionary

jellyfish

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noun jel·ly·fish \ ˈjel-ē-ˌfish \

medical Definition of jellyfish

:a free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells