This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 芁 is uncertain. It visually combines 艹 (grass) and 几 (table), but the original meaning and component relationship are unclear.
With no clear meaning, picture grass 艹 growing over a small table 几, as if nature is reclaiming an abandoned object. This image can help you remember the shape, but the meaning remains uncertain.
For コウ, imagine a coat (コート) draped over the grass-covered table: coat -> コウ, tying the reading to the visual scene.
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