Source : Webster's Revised Unabridged Dictionary (1913)

Entozoon \En`to*zo"["o]n\, n.; pl. {Entozoa}. [NL. See
   {Entozoa}.] (Zo["o]l.)
   One of the Entozoa.

Source : WordNet®

entozoon
     n : any of various parasites that live in the internal organs of
         animals (especially intestinal worms) [syn: {endoparasite},
          {entoparasite}, {entozoan}, {endozoan}]