What are the frequencies in a complex wave besides the fundamental frequency commonly referred to as?

The frequencies in a complex wave other than the fundamental frequency are commonly referred to as overtones. When a musical instrument produces sound, it vibrates at a fundamental frequency, which is the lowest frequency and determines the pitch of the sound. In addition to this fundamental frequency, the instrument also produces additional frequencies, which are higher in pitch and occur at integer multiples of the fundamental. These additional frequencies contribute to the timbre or color of the sound and can be categorized as overtones.

While the term "harmonics" is often used interchangeably with overtones, it specifically refers to the frequencies that are integer multiples of the fundamental frequency. Therefore, the term "overtones" encompasses all frequencies above the fundamental, including harmonics, but is generally broader. The term "partial frequencies" can also be used to describe any component frequency in a sound wave, including both fundamental and overtones, but does not specifically denote the additional frequencies above the fundamental. Thus, using "overtones" captures the essence of referring to these additional frequencies distinctly from the fundamental frequency itself.