This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
岲 combines 山 (mountain) and 兄 (elder brother), but the historical origin and original meaning are uncertain. It may have been a place name or a variant form.
With no clear meaning, picture a mountain 山 where an elder brother 兄 stands, but what he does there is unknown.
For コウ, imagine the elder brother 兄 on the mountain 山 calling out 'Kou!' to the valley below: Kou -> コウ.
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