pro·to·zo·an  (prō'tə-zō'ən)  n. pl. pro·to·zo·ans or pro·to·zo·a (-zō'ə) also pro·to·zo·ons Any of a large group of single-celled, usually microscopic, eukaryotic organisms, such as amoebas, ciliates, flagellates, and sporozoans. [From New Latin Protozōa, former subkingdom name : proto- + -zōa, pl. of -zōon, -zoon.] pro'to·zo'an, pro'to·zo'al, pro'to·zo'ic adj. |