This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
蔃 is a rare character composed of 艹 (grass) and 强 (strong). The exact historical development and original meaning are uncertain.
The top 艹 suggests a plant, and the bottom 强 suggests strength. Imagine a strong, resilient plant, but its exact meaning is unclear.
For キョウ, picture a strong plant growing in Kyoto (京都, きょうと): Kyoto -> キョウ, and the plant is as strong as the city's history.
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