弦
xián · HSK 7
string of musical instrument
🏹🎻 弓 bow radical + 玄 (phonetic, ~xuán) = the string stretched on a bow
The 弓 on the left is the bow radical; 玄 on the right carries the sound (xuán, near xián). The taut line on a bow extends to any taut string: a violin string, a watchspring, even a chord cutting across a curve.
弦 — bow 弓 + dark/profound 玄
A semantic-phonetic compound: 弓 (bow) gives the meaning, while 玄 supplies the sound. It originally referred to the taut bowstring, then extended to strings on musical instruments like the qin and pipa, and later to the mathematical sense of a chord or hypotenuse.