Source : Webster's Revised Unabridged Dictionary (1913)

Protozoan \Pro`to*zo"an\, a. (Zo["o]l.)
   Of or pertaining to the {Protozoa}. -- n. One of the
   Protozoa.

Source : WordNet®

protozoan
     adj : of or relating to the Protozoa [syn: {protozoal}, {protozoic}]
     n : any of diverse minute acellular or unicellular organisms
         usually nonphotosynthetic [syn: {protozoon}]
     [also: {protozoa} (pl)]