ae·ci·o·spore (??s?-?-spôr?, -sh?-)n. A binucleate spore of a rust fungus, formed in a chainlike series in an aecium.[aeci(um) + spore.]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.aeciospore (?i?s???sp??) n (Botany) any of the spores produced in an aecium of the rust fungi, which spread to and infect the primary host. Also called: aecidospore [C20: from aecium + spore]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ae?ci?o?spore (?i si ??sp?r, -?spo?r, ?i ?i-) n. a spore borne by an aecium. [1875?80] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.