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
While the immortal jellyfish evokes our wonder and curiosity, the deep sea and its creatures can often stir a deep, primal fear in us.
—
Scott Travers, Forbes.com, 26 May 2026
Osaka told Vogue that the ludicrous Aussie Open outfit was inspired by a picture of a jellyfish that her two-year-old daughter got excited about.
—Mark Harris Outkick, FOXNews.com, 26 May 2026
These jellyfish are commonly seen in the open ocean but can drift closer to shore on occasion.
—Veronica Fernandez-Alvarado, Sacbee.com, 20 May 2026
The optimization approach focused on creating an asymmetric motion pattern similar to natural jellyfish, where the contraction phase is faster than recovery.
—Neetika Walter, Interesting Engineering, 14 May 2026
See All Example Sentences for jellyfish
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Scott Travers, Forbes.com, 26 May 2026
Osaka told Vogue that the ludicrous Aussie Open outfit was inspired by a picture of a jellyfish that her two-year-old daughter got excited about.
—Mark Harris Outkick, FOXNews.com, 26 May 2026
These jellyfish are commonly seen in the open ocean but can drift closer to shore on occasion.
—Veronica Fernandez-Alvarado, Sacbee.com, 20 May 2026
The optimization approach focused on creating an asymmetric motion pattern similar to natural jellyfish, where the contraction phase is faster than recovery.
—Neetika Walter, Interesting Engineering, 14 May 2026
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. 2026.
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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