hydroid

UK: /ˈhaɪdrɔɪd/ US: (hī′droid)

WordReference Random House Unabridged Dictionary of American English © 2026

hy•droid  (hī′droid), adj. 

1. Invertebrates noting or pertaining to that form of hydrozoan that is asexual and grows into branching colonies by budding.

n. 

2. Invertebrates the phase of a hydrozoan coelenterate that consists of polyp forms usually growing as an attached colony.

• hydr(a) + -oid 1860–65

Collins Concise English Dictionary © HarperCollins Publishers::

hydroid / ˈhaɪdrɔɪd/ adjective

1. of or relating to the Hydroida, an order of colonial hydrozoan coelenterates that have the polyp phase dominant
2. (of coelenterate colonies or individuals) having or consisting of hydra-like polyps

noun

1. a hydroid colony or individual

Etymology: 19th Century: from hydra + -oid