harmonic

1. relating to or characterized by harmony.

   a basic four-chord harmonic sequence

2. relating to a harmonic progression.

   the resonant frequencies of the vibrations bear simple harmonic relationships to each other

3. using or produced by the application of a harmonic.

   harmonic charts

1. 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.
2. a component frequency of an oscillation or wave.
3. a division of the zodiacal circle by a specified number, used in the interpretation of a birth chart.

   the fifth harmonic

late 16th century (in the sense ‘relating to music, musical’): via Latin from Greek harmonikos, from harmonia (see harmony).