'泛音' (fàn yīn) literally combines '泛' (fàn), meaning 'to spread', 'to float', or 'general/overarching', and '音' (yīn), meaning 'sound' or 'tone'. In music theory, it refers to harmonics — the pure, bell-like tones produced by lightly touching a vibrating string at specific nodal points, rather than pressing it fully to the fingerboard. These overtones occur naturally in the harmonic series and are fundamental to string and wind instrument technique.

While not exclusive to any one instrument, 泛音 is especially important in guqin, pipa, and erhu performance, where controlled harmonics add clarity and resonance. It also appears in Western classical music contexts when discussing acoustics or violin technique — though Chinese musicians often use 泛音 even when referring to Western instruments. The term carries no colloquial or metaphorical usage; it remains strictly technical and musical.