/ Dictionary / Index P pneumonitis: Meaning and Definition of Find definitions for: pneu•mo•ni•tis Pronunciation: (n"mu-nī'tis, ny"-), [key] — n. Pathol. inflammation of the lung caused by a virus or exposure to irritating substances. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: pneumonitis (Thesaurus) pneumonic plague pneumono- Related Content Daily Word Quiz: ontiguous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language