/ Dictionary / Index P periostitis: Meaning and Definition of Find definitions for: per•i•os•ti•tis Pronunciation: (per"ē-o-stī'tis), [key] — n. Pathol. inflammation of the periosteum. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. periosteum periostracum Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language