type of harp
箜 refers to a type of harp, specifically an ancient Chinese angular harp. Its meaning is narrowly tied to this musical instrument.
箜 combines 竹 (bamboo) with 空 (empty, sky), likely as a phono-semantic compound where 空 hints at the sound and bamboo indicates the material of the instrument.
Bamboo 竹 over emptiness 空: imagine a harp made of bamboo, its hollow body resonating with sound from the empty space inside.
For ク, picture a cool, resonant note from the harp echoing in an empty room: cool -> ク, and the sound fills the space.
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konghou (ancient Chinese harp)