/ Dictionary / Index E exospore: Meaning and Definition of Find definitions for: ex•o•spore Pronunciation: (ek'su-spôr", -spōr"), [key] — n. Bot., Mycol. the outer coat of a spore. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. exosphere exostosis Related Content Daily Word Quiz: cetacean Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language