The Collaborative International Dictionary of English v.0.48:

Entozoa \En`to*zo"a\, n. pl. [NL., fr. Gr. ? within + zw,on an
   animal.] (Zo["o]l.)
   1. A group of worms, including the tapeworms, flukes,
      roundworms, etc., most of which live parasitically in the
      interior of other animals; the Helminthes.
      [1913 Webster]

   2. An artificial group, including all kinds of animals living
      parasitically in others. Entozoal

The Collaborative International Dictionary of English v.0.48:

Entozoon \En`to*zo"["o]n\, n.; pl. Entozoa. [NL. See
   Entozoa.] (Zo["o]l.)
   One of the Entozoa.
   [1913 Webster]