'Protozoon' definitions:

Definition of 'protozoon'

(from WordNet)
noun
Any of diverse minute acellular or unicellular organisms usually nonphotosynthetic [syn: protozoan, protozoon]

Definition of 'Protozoon'

From: GCIDE
  • Protozoon \Pro`to*zo"["o]n\ (-[o^]n), n.; pl. Protozoa. [NL.] (Zool.) (a) One of the Protozoa. (b) A single zooid of a compound protozoan. [1913 Webster]