zo·on (z???n?)n. pl. zo·ons or zo·a (z???) Archaic 1. An individual animal produced from an egg.2. A zooid.[New Latin z?on, from Greek z?ion, z?on, living being; see gwei- in Indo-European roots.]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.zoon (?z???n) n, pl zoa (?z???) or zoons (Zoology) a less common term for zooid1[C19: from New Latin, from Greek z?ion animal; related to Greek z?? life] zo?onal adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014