This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 龣 is uncertain. It combines 龠 (a reed instrument) with 彔, but the original meaning and component function are unclear.
Without a clear meaning, focus on the shape: a complex left side 龠 (a panpipe-like instrument) next to 彔 (a carving or recording tool).
For カク, imagine a carved (彔) flute (龠) making a sharp 'kaku' sound: kaku -> カク.
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