noun pl \ˌprōt-ə-ˈzō-ə\

Definition of PROTOZOA

: a phylum or subkingdom of chiefly motile unicellular protists (as amebas, trypanosomes, sporozoans, and paramecia) that consist of a protoplasmic body either naked or enclosed in an outer covering, that have holophytic, saprophytic, or holozoic modes of nourishment, that reproduce asexually by nuclear division usually with a more or less modified mitosis associated with cytoplasmic binary fission or with multiple fission or budding or often sexually by various means, that have the life cycle simple (as in an ameba) or extremely complex (as in many sporozoans), that are represented in almost every kind of habitat, and that include pathogenic parasites of humans and domestic animals—compare metazoa 1

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