/ Dictionary / Index E exostosis: Meaning and Definition of Find definitions for: ex•os•to•sis Pronunciation: (ek"so-stō'sis, -su-), [key] — pl. -ses the abnormal formation of a bony growth on a bone or tooth. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: exostosis (Thesaurus) exospore exoteric 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