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
The species is the largest of the 200 species of jellyfish in the world.
—
Mike Stunson, Miami Herald, 24 June 2025
Bluebottles in the Sea What looks like a serene, single jellyfish floating in the vastness of the sea is actually a colony of specialized individuals called polyps.
—Jenny Lehmann, Discover Magazine, 20 June 2025
That equates roughly to once every third stroke – an aggressive form of exposure therapy for someone who claims to be terrified of jellyfish.
—George Ramsay, CNN Money, 30 Apr. 2025
The aquarium has been a pioneer from the start, unveiling the world’s first living kelp forest exhibit and debuting large-scale displays of jellyfish—hypnotic creatures that pulse rhythmically through the glowing blue waters.
—Brittany Anas, Forbes.com, 10 July 2025
See All Example Sentences for jellyfish
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Mike Stunson, Miami Herald, 24 June 2025
Bluebottles in the Sea What looks like a serene, single jellyfish floating in the vastness of the sea is actually a colony of specialized individuals called polyps.
—Jenny Lehmann, Discover Magazine, 20 June 2025
That equates roughly to once every third stroke – an aggressive form of exposure therapy for someone who claims to be terrified of jellyfish.
—George Ramsay, CNN Money, 30 Apr. 2025
The aquarium has been a pioneer from the start, unveiling the world’s first living kelp forest exhibit and debuting large-scale displays of jellyfish—hypnotic creatures that pulse rhythmically through the glowing blue waters.
—Brittany Anas, Forbes.com, 10 July 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 1 Aug. 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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