Definition of medusoid in US English:



  • 1Relating to or resembling a medusa or jellyfish.

    • ‘The trachyline Hydrozoans possess only the medusoid form.’
    • ‘Free-living medusoid hydrozoans can be hard to tell from scyphozoans, but hydrozoan medusae generally have a muscular shelf, or velum, projecting inward from the margin of the bell.’
    • ‘Some of these medusoid fossils show clear impressions of tentacles around their margins.’
    • ‘Although they share traits with the scyphozoans and hydrozoans, cubozoans also possess traits found in neither of the two other medusoid classes.’
    • ‘The medusoid Aspidella is virtually ubiquitous; Hiemalora, Nemiana, Eoporpita, and Tribrachidium also are distributed in a wide range of facies.’
    1. 1.1 Relating to or denoting the medusa phase in the life cycle of a coelenterate.
      Compare with polypoid (sense 1)
      • ‘A life cycle including both polypoid and medusoid phases that can be separate in space and scarcely overlapping in time characterizes many hydrozoans and most scyphozoans.’
      • ‘A few, such as Hydra, are solitary polyps that lack a medusoid stage.’
      • ‘Anthozoan cnidarians lack the medusoid lifestage found in other Cnidaria.’
      • ‘The Scyphozoa, or jellyfish, are an exclusively marine class in which the medusoid stage dominates.’
      • ‘Hydra never goes through a medusoid stage, and spends its entire life as a polyp.’


  • 1A medusa or jellyfish.

    • ‘Others appear to have been solitary coelenterate medusoids attached to the sea floor.’
    • ‘In colonial hydroids, the individual polyps, or zooids, are differentiated for different functions: gastrozooids feed, dactylozoids capture prey, and gonozooids give rise to medusoids with gametes.’
    • ‘Common medusoids and fronds, however, do not generally show this restriction.’
    • ‘These are much more restricted in their distribution, possibly because they did not have as much time to disperse as the fronds and medusoids, but probably also because of environmental restrictions on their range.’
    • ‘However, this is not statistically significant for the bilaterians and only weakly significant for medusoids.’
    1. 1.1 A medusoid reproductive bud.