Definition from Wiktionary, the free dictionary
Ultimately from Ancient Greek ὕδωρ (húdōr, “water”) + ζῷον (zōîon, “animal”). This definition is lacking an etymology or has an incomplete etymology. You can help Wiktionary by giving it a proper etymology.
hydrozoa (plural only)
- (biology) a large group of marine animals, of the class Hydrozoa, whose life cycles contain a sexual and asexual stage