/ Dictionary / Index D diatonicism: Meaning and Definition of Find definitions for: di•a•ton•i•cism Pronunciation: (dī"u-ton'u-siz"um), [key] — n. the use of diatonic harmony; composition in a diatonic idiom. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. diatonic diatreme Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language