zy·go·spore (z??g?-spôr?, z?g??-)n. A thick-walled diploid or multinucleate spore formed by the union of similar gametes in certain fungi and algae.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.zygospore (?za?????sp??; ?z??-) n (Biology) a thick-walled sexual spore formed from the zygote of some fungi and algae ?zygo?sporic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014zy?go?spore (?za? g??sp?r, -?spo?r, ?z?g ?-) n. a cell formed by fusion of two similar gametes, as in certain algae and fungi. [1860?65] zy`go?spor?ic (-?sp?r ?k, -?sp?r-) adj. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.