Definition of harmonic
adjective
1of, relating to, or characterized by musical harmony:a basic four-chord harmonic sequence Music relating to or denoting a harmonic or harmonics.
2 Mathematics of or relating to a harmonic progression. Physics of or relating to component frequencies of a complex oscillation or wave. Astrology using or produced by the application of a harmonic:harmonic charts
noun
1 Music an overtone accompanying a fundamental tone at a fixed interval, produced by vibration of a string, column of air, etc., in an exact fraction of its length. a note produced on a musical instrument as an overtone, e.g., by lightly touching a string while sounding it.
2 Physics a component frequency of an oscillation or wave. Astrology a division of the zodiacal circle by a specified number, used in the interpretation of a birth chart.