This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嵓 combines 山 (mountain) with 品 (goods, items), but the exact historical development and original meaning are uncertain.
The top is 山 (mountain) and the bottom is 品 (goods). Picture a mountain stacked with mysterious goods, but its true meaning remains hidden.
For ガン, imagine a lone gun on top of the mountain goods: gun -> ガン, though the kanji's meaning is unclear.
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