Definition of hydroid in English:


Line breaks: hy|droid
Pronunciation: /ˈhʌɪdrɔɪd


  • A coelenterate of an order which includes the hydras. They are distinguished by the dominance of the polyp phase.
    • Order Hydroida, class Hydrozoa
    More example sentences
    • Aside from its temporary and permanently resident fish, the underside is decorated with sponges, hydroids, tunicates, tube worms, cup corals and anemones.
    • There were dense walls of soft corals, sponges, anemones and hydroids, nudibranchs, creepy-crawlies and lots of fish.
    • On the walls are a riot of soft corals, sponges, hydroids and anemones in all shapes and sizes.


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  • 1Relating to coelenterates of the hydroid group.
    More example sentences
    • He had shown that hydroid jellyfish known as naked-eyed medusae reproduce not only by spewing eggs, but also by asexual budding, which he found marvelous to behold.
    • The hydroid tissues, in particular, are the general run of moss water storage cells and are probably only remotely related to the xylem of tracheophytes.
    • Before long, similar green proteins were detected in many bioluminescent coelenterates including various medusae, apparently all luminescent hydroid polyps, and a few others.
  • 1.1 another term for polypoid ( sense 1).


mid 19th century: from hydra + -oid.

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