zoological gardenn. See zoo.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.zoological garden n (Zoology) the formal term for zoo Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014zoo (zu) n., pl. zoos. 1. Also called zoological garden. a parklike area in which live animals are kept in cages or large enclosures for public exhibition. 2. a place, activity, or group marked by chaos or unrestrained behavior. [1840?50; first two syllables of zoological garden taken as one syllable] zoo?ey, adj. zoo?i?er, zoo?i?est. zoo- a combining form meaning ?living being,? ?animal?: zooplankton. Also, esp. before a vowel,zo-. [comb. form representing Greek zôion animal] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.