1. The branch of biology that deals with animals and animal life, including the study of the structure, physiology, development, and classification of animals.
2. The animal life of a particular area or period: the zoology of Alaska; the zoology of the Pleistocene.
3. The characteristics of a particular animal group or category: the zoology of mammals.
4. A book or scholarly work on zoology.

Usage Note: Traditionally, the first syllable of zoology has been pronounced as (ō), rhyming with toe. However, most likely due to the familiarity of the word zoo (which is merely a shortened form of zoological garden), the pronunciation of the first syllable as (ōō) is also commonly heard. In 1999, 88 percent of the Panelists found the (zō-) pronunciation acceptable, and 60 percent found the (zōō-) pronunciation acceptable, with 68 percent using the (zō-) pronunciation and 32 percent using the (zōō-) pronunciation in their own speech. Thus, while both pronunciations can be considered acceptable, the (zō-) pronunciation may be perceived as more correct.