Illustration of jellyfish
- jellyfish 1a
jellyfish
noun
jel·ly·fish
ˈje-lē-ˌfish 
1
a
: the typically free-swimming, bell-shaped, usually sexually-reproducing solitary or colonial form of a cnidarian in which the whorls of tentacles lined with nematocysts arise and hang down from the margin of the nearly transparent, gelatinous bell : medusa
especially
: a large medusa characteristic of the siphonophores and scyphozoans (such as the sea nettle or box jellyfish)
b
c
2
: a person lacking backbone or firmness
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 on the Web
Of course, Yamagata is a long way to go just to peep some jellyfish, so combine a visit with the misty temples of nearby Dewa Sanzan, three mountains sacred to the ascetics of the esoteric Shugendo religion.
—
Jessica Kozuka, Travel + Leisure, 27 May 2025
Tiny sea creatures living in the seaweed, like jellyfish and sea lice, can also cause skin rashes and blisters.
—Michelle Marchante, Miami Herald, 29 Apr. 2025
Guides explain the science behind the spectacle, including a briefing on upside-down jellyfish that thrive in the area.
—Alexandra Gillespie, Outside Online, 28 Apr. 2025
While exploring the wreck of USS Yorktown during Dive 06 of the Papahānaumokuākea ROV and Mapping expedition, researchers imaged this colorful red jellyfish, which may be a new species.
—Kerry Breen, CBS News, 23 Apr. 2025
See All Example Sentences for jellyfish
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Jessica Kozuka, Travel + Leisure, 27 May 2025
Tiny sea creatures living in the seaweed, like jellyfish and sea lice, can also cause skin rashes and blisters.
—Michelle Marchante, Miami Herald, 29 Apr. 2025
Guides explain the science behind the spectacle, including a briefing on upside-down jellyfish that thrive in the area.
—Alexandra Gillespie, Outside Online, 28 Apr. 2025
While exploring the wreck of USS Yorktown during Dive 06 of the Papahānaumokuākea ROV and Mapping expedition, researchers imaged this colorful red jellyfish, which may be a new species.
—Kerry Breen, CBS News, 23 Apr. 2025
See All Example Sentences for jellyfish
Cite this Entry
“Jellyfish.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/jellyfish. Accessed 4 Jun. 2025.
Copy CitationKids Definition
jellyfish
noun
jel·ly·fish
ˈjel-ē-ˌfish
1
: any of numerous free-swimming coelenterate animals that reproduce sexually and have a jellylike, saucer-shaped, and usually nearly transparent body and tentacles with stinging cells
2
: any of various sea animals that resemble a jellyfish
Medical Definition
jellyfish
noun
jel·ly·fish
ˈjel-ē-ˌfish
: 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
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