jellyfish

[jel-ee-fish] /ˈdʒɛl iˌfɪʃ/

noun, plural (especially collectively) jellyfish (especially referring to two or more kinds or species) jellyfishes.

any of various marine coelenterates of a soft, gelatinous structure, especially one with an umbrellalike body and long, trailing tentacles; medusa.

Informal. a person without strong resolve or stamina; an indecisive or weak person.

Origin

1700-10; 1910-15 for def 2; jelly + fish

Examples from the web for jellyfish

Set against the sea, he was as inconsequential as a jellyfish.
jellyfish are common visitors to many beaches, so teach kids to keep their eyes peeled for these stinging animals.
Their nets are trapping jellyfish: giant, gelatinous, wobbly and worthless.
In this case, to prove the point, the gene they introduced was for green fluorescent protein-a molecule derived from jellyfish.
jellyfish come in a variety of shapes, sizes and colors.
New research is suggesting that jellyfish and other small ocean dwellers might play a big role in mixing the ocean's waters.
Some jellyfish, algae and bacteria produce light-activated ion pumps and channels.
Already, human impacts on the ocean are large, from spurring jellyfish to dominate to boosting algae blooms and dead zones.
Increases in jellyfish blooms also are likely to be part of the process.
jellyfish are among the only living things to thrive in the oxygen-starved waters of expanding dead zones.

British Dictionary definitions for jellyfish

/ˈdʒɛlɪˌfɪʃ/

noun (pl) -fish, -fishes

any marine medusoid coelenterate of the class Scyphozoa, having a gelatinous umbrella-shaped body with trailing tentacles

any other medusoid coelenterate

(informal) a weak indecisive person

Word Origin and History for jellyfish

popular name of the medusa and similar sea-creatures, 1796, from jelly (n.) + fish (n.). Earlier it had been used of a type of actual fish (1707).

jellyfish in Medicine

jellyfish jel·ly·fish (jěl'ē-fĭsh')
n. pl jellyfish or jel·ly·fish·es

Any of numerous marine coelenterates of the class Scyphozoa, some poisonous species of which notably the Portuguese man-of-war, produce a toxin that can be injected into the skin by nematocysts on the tentacles, causing linear wheals.
Any of various similar or related coelenterates.