The Collaborative International Dictionary of English v.0.48:

Microzoa \Mi`cro*zo"a\ (m[imac]`kr[-o]*z[=o]"[.a]), n. pl. [NL.,
   fr. Gr. mikro`s small + zw^,on an animal.] (Zool.)
   The Infusoria.
   [1913 Webster]