[hahy-druh-zoh-uh
n] 
| 1. | any freshwater or marine coelenterate of the class Hydrozoa, including free-swimming or attached types, as the hydra, in which one developmental stage, either the polyp or medusa, is absent, and colonial types, as the Portuguese man-of-war, in which both medusa and polyp stages are present in a single colony. |
| 2. | belonging or pertaining to the Hydrozoa. |
| hy·dro·zo·an (hī'drə-zō'ən) n. Any of numerous coelenterates of the class Hydrozoa, including the freshwater hydras, hydroids, hydrocorals, and siphonophores. adj. Of, relating to, or belonging to the class Hydrozoa. [From New Latin Hydrozōa, class name : hydro- + -zōa, pl. of -zōon, -zoon.] |