What does jellyfish mean?
A jellyfish is a soft, gelatinous marine animal related to sea anemones and corals rather than to ordinary fish. Most jellyfish drift through the water with their rounded bells, while their tentacles capture prey and can deliver stings. Some species, including the familiar moon jelly, have delicate, translucent bodies, whereas others have long, powerful tentacles. The word is also used informally for a person who is timid, weak, or unwilling to face difficulty, though this figurative sense is disparaging. In culinary contexts, the prepared tentacles of some jellyfish are eaten as a delicacy in parts of East and Southeast Asia. The name combines 'jelly,' referring to the animal's soft or gelatinous appearance, with 'fish,' a traditional general term for sea creatures.
A chiefly marine, gelatinous animal with a bell-shaped or umbrella-shaped body and trailing tentacles, belonging to the cnidarians.
"A jellyfish washed ashore after the storm."
The plural is usually 'jellyfish.'
Informally, a person regarded as timid, weak, or cowardly.
"His friends accused him of being a jellyfish when he backed out of the challenge."
This sense is informal and disparaging.
The plural is normally unchanged: one jellyfish, many jellyfish. 'Jellyfishes' is also accepted in formal and scientific contexts.
"Hundreds of jellyfish filled the sheltered bay."
A jellyfish can survive without a brain or a heart, yet its simple body can still sting, swim, and respond to light.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does jellyfish come from?
The compound 'jellyfish' developed in English from 'jelly' and 'fish.' 'Jelly' comes through Old French from the Latin 'gelare,' meaning to freeze or congeal, while 'fish' is Old English and originally referred broadly to aquatic animals rather than only to the modern biological group. The compound therefore preserves an older sense of the word, even though jellyfishes are cnidarians and are not true fish.
How jellyfish is actually used
The animal meaning is neutral and standard. The figurative meaning is informal and generally derogatory, especially in British and American English. The plural is usually the unchanged form 'jellyfish,' although 'jellyfishes' is also used.
Easily confused with jellyfish
A jellyfish is a cnidarian with a soft, bell-shaped body, whereas a squid is a mollusk with a distinct head, mantle, and tentacles.
A Portuguese man o' war is a floating hydrozoan colony with a sail-like structure, not a true jellyfish.