/ Dictionary / Index H harmonic motion: Meaning and Definition of Find definitions for: harmon'ic mo'tion Pronunciation: [key] — Physics. Physics. periodic motion consisting of one or more vibratory motions that are symmetric about a region of equilibrium, as the motion of a vibrating string of a musical instrument. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. harmonic minor scale harmonicon Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language