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
However, not all jellyfish are as scary.
—
Taryn White, Travel + Leisure, 29 Oct. 2025
The presence of a semipermeable faunal boundary in the North Atlantic Current was suggested by the absence, below the 47th parallel, of knobless Botrynema brucei ellinorae jellyfish.
—Rafil Kroll-Zaidi, Harpers Magazine, 29 Oct. 2025
Created by a team led by Tao Kai at the School of Mechanical and Electrical Engineering of Northwestern Polytechnical University in Xi’an, Shaanxi province, the transparent robot mimics the movements and appearance of a real jellyfish.
—Bojan Stojkovski, Interesting Engineering, 25 Oct. 2025
The ultra-chunky model, which is based on the Adistar Cushion 3 running shoe from 2005, features a sculptural midsole inspired by the fluid shape of a jellyfish.
—Stephen Garner, Footwear News, 25 Oct. 2025
See All Example Sentences for jellyfish
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Taryn White, Travel + Leisure, 29 Oct. 2025
The presence of a semipermeable faunal boundary in the North Atlantic Current was suggested by the absence, below the 47th parallel, of knobless Botrynema brucei ellinorae jellyfish.
—Rafil Kroll-Zaidi, Harpers Magazine, 29 Oct. 2025
Created by a team led by Tao Kai at the School of Mechanical and Electrical Engineering of Northwestern Polytechnical University in Xi’an, Shaanxi province, the transparent robot mimics the movements and appearance of a real jellyfish.
—Bojan Stojkovski, Interesting Engineering, 25 Oct. 2025
The ultra-chunky model, which is based on the Adistar Cushion 3 running shoe from 2005, features a sculptural midsole inspired by the fluid shape of a jellyfish.
—Stephen Garner, Footwear News, 25 Oct. 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 31 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share