protozoan
pro.to.zo.an \.pro-t-*-'zo--*n\ \-'zo--ik\ n [NL Protozoa, phylum name, fr. prot- + -zoa] : any of a phylum or subkingdom (Protozoa) of minute protoplasmic acellula r or unicellular animals with varied morphology and physiology and often complex life cycles that are represented in most habitats including the parasitic - protozoan aj