Definition of: zooid

(zō′oid) noun
1. Biol. Any organism, usually very small, capable of spontaneous movement and independent existence, as a spermatozoon.
2. Zool. a One of the distinct members of a compound or colonial organism, as in a bryozoan. b A free-swimming organism produced as a stage in the life cycle of a jellyfish.
—adjective Having essentially the nature of an animal: also zo·oi·dal (zō·oid′l). [<ZO- + -OID]