The Collaborative International Dictionary of English v.0.48:

Zoologist \Zo*ol"o*gist\, n. [Cf. F. zoologiste.]
   One who is well versed in Zoology.
   [1913 Webster]

WordNet (r) 3.0 (2006):

zoologist
    n 1: a specialist in the branch of biology dealing with animals
         [syn: zoologist, animal scientist]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "zoologist":
   anatomist, animal physiologist, anthropologist, bacteriologist,
   biochemist, biologist, biometrist, biophysicist, botanist,
   conchologist, cytologist, ecologist, entomologist, ethologist,
   geneticist, helminthologist, herpetologist, ichthyologist,
   malacologist, mammalogist, natural scientist, naturalist,
   ophiologist, ornithologist, physiologist, protozoologist,
   taxidermist, zoo-ecologist, zoographer, zoonomist, zoopathologist,
   zoophysicist, zootaxonomist