An Etymological Dictionary of Astronomy and Astrophysics

A note of lesser intensity and higher frequency than the fundamental note, and superimposed upon the latter to give a note of characteristic quality. Overtones whose frequencies are an integral
multiple of the fundamental are said to form a harmonic series. The
fundamental with a frequency f₁ is the first harmonic. The frequency 2f₁ is the first overtone
and so on.

See also: → over-; → tone.