/ Dictionary / Index Q quarter tone: Meaning and Definition of Find definitions for: quar'ter tone" Pronunciation: [key] — Music. Music. an interval equivalent to half of a semitone. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. quarterstaff quarter-wave plate Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language