protozoan Syllabification: (pro·to·zo·an)Pronunciation: /ˌprōtəˈzōən/ ZoologyDefinition of protozoan noun a single-celled microscopic animal of a group of phyla of the kingdom Protista, such as an ameba, flagellate, ciliate, or sporozoan. adjective relating to or denoting protozoans. Derivatives protozoal adjective protozoicPronunciation: /-ˈzōik/ adjective protozoonPronunciation: /-ˈzōˌän/ noun protozoan in other Oxford dictionaries Definition of protozoan in the British & World English dictionary