The prefix zoo-, which is pronounced with two syllables, comes from Greek zoion, meaning ?animal, living being.? We know this prefix best from the one-syllable word zoo. Zoo is a popular shortening of the longer, more formal zoological garden, which was originally a park where wild animals were kept on display. Zoological is the adjective form of the noun zoology, which means ?the study of animals.? Zoology is thus part of biology, which means ?the study of life.?    1