zy·go·mor·phic (z??g?-môr?f?k, z?g??-) also zy·go·mor·phous (-f?s)adj. Botany Having bilateral symmetry, as the flowers of a pea plant.zy?go·mor?phy n.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.