- The sinusoidal component of an arc voltage that is a multiple of the fundamental wave frequency.
- For a complex signal, wave, sound, or vibration which is periodic, a component whose frequency is a whole-number multiple of the fundamental frequency. The fundamental frequency is also called fundamental component, or first harmonic. The frequency of the second harmonic is twice that of the first harmonic, the third harmonic is three times the first harmonic, and so on. Any even-numbered multiple of the first harmonic is called an even harmonic, while odd-numbered multiples are called odd harmonics. Overtones are the same as harmonics, except that the first overtone is the same as the second harmonic, the second overtone is the same as the third harmonic, and so on. Also called harmonic component.