- For a complex signal, wave, or vibration which is periodic, the sinusoidal component having the lowest frequency. All integral multiples are called harmonics, the second harmonic being twice the fundamental frequency, the third harmonic being three times the fundamental frequency, and so on. Any even-numbered multiple of the fundamental frequency is called an even harmonic, while odd-numbered multiples are called odd harmonics. Also called fundamental, fundamental component, or first harmonic.
- For an oscillating system, the lowest natural resonance frequency.
- synonymfirst harmonic
- synonymfundamental component