'Jellyfish' definitions:

Definition of 'jellyfish'

From: WordNet
noun
Large siphonophore having a bladderlike float and stinging tentacles [syn: Portuguese man-of-war, man-of-war, jellyfish]
noun
Any of numerous usually marine and free-swimming coelenterates that constitute the sexually reproductive forms of hydrozoans and scyphozoans

Definition of 'Jellyfish'

From: GCIDE
  • Jellyfish \Jel"ly*fish`\, n. (Zool.) Any one of the acalephs, esp. one of the larger species, having a jellylike appearance. See Medusa and acaleph. [1913 Webster]

Synonyms of 'jellyfish'

From: Moby Thesaurus