n. & adj.
--n. (also protozoon) (pl. protozoa or protozoans) any usu. unicellular and microscopic organism of the subkingdom Protozoa, including amoebae and ciliates.
--adj. (also protozoic) of or relating to this phylum.
Derivatives:
protozoal adj.
Etymology: mod.L (as PROTO-, Gk zoion animal)