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 production was plagued by hurricanes, tsunami warnings, stinging jellyfish and several injuries — including Costner, who almost died while riding out a storm stranded atop a mast after his safety line had snapped.
—
Peter Kiefer, HollywoodReporter, 8 Oct. 2025
While Nathan runs around pulling his hair and Josh finds a way to plate nuts with eggs, Max tries to amuse himself and Aesha by playing with a jellyfish.
—Rafaela Bassili, Vulture, 7 Oct. 2025
These pretty pink jellyfish are carnivorous and have stinging tentacles that can reach up to 70 feet long.
—Meghan Overdeep, Southern Living, 25 Sep. 2025
As with the jellyfish and ctenophores, many of these lose their transparency at depth, becoming red over at least part of their bodies.
—Literary Hub, 25 Sep. 2025
See All Example Sentences for jellyfish
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Peter Kiefer, HollywoodReporter, 8 Oct. 2025
While Nathan runs around pulling his hair and Josh finds a way to plate nuts with eggs, Max tries to amuse himself and Aesha by playing with a jellyfish.
—Rafaela Bassili, Vulture, 7 Oct. 2025
These pretty pink jellyfish are carnivorous and have stinging tentacles that can reach up to 70 feet long.
—Meghan Overdeep, Southern Living, 25 Sep. 2025
As with the jellyfish and ctenophores, many of these lose their transparency at depth, becoming red over at least part of their bodies.
—Literary Hub, 25 Sep. 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 17 Oct. 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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