zy·gote (z??g?t?)n.1. The cell formed by the union of two gametes, especially a fertilized ovum before cleavage.2. The organism that develops from a zygote.[From Greek zug?tos, yoked, from zugoun, to yoke; see yeug- in Indo-European roots.]zy·got?ic (-g?t??k) adj.zy·got?i·cal·ly adv.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.