a phylum or group of phyla that comprises the single-celled microscopic animals, which include amebas, flagellates, ciliates, sporozoans, and many other forms. They are now usually treated as a number of phyla belonging to the kingdom Protista.
(as plural noun protozoa) organisms of the Protozoa group.
Origin:
modern Latin (plural), from proto- 'first' + Greek zōion 'animal'
