inharmonicity

In music, "inharmonicity" refers to sounds where the overtones are not exact multiples of the fundamental frequency. This is in contrast to "harmonicity," where overtones have frequencies that are simple ratios of the fundamental.1

Some musical instruments, like drums or cymbals, produce nonharmonic overtones, contributing to their unique timbre or tone color. The shape of an instrument's bore can also influence harmonicity; for instance, bores that flare too quickly can create nonharmonic overtones, resulting in less musical sounds.12

In phonetics, "inharmonic theory" suggests that reinforcing vibrations in vocal articulation don't need to be multiples of the fundamental vocal-cord note. In tuning, "enharmonic" refers to notes that sound the same but are notated differently, such as F♯ and G♭.34