This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
楺 combines 木 (tree) with 柔 (soft, gentle). The exact historical development is uncertain, but it likely originally referred to a type of tree or wood with flexible properties.
A tree 木 that is soft and flexible 柔: imagine a young sapling that bends easily without breaking.
For ジョウ, imagine a soft young tree being gently bent into the shape of a 'J' by a gardener named Joe: Joe -> ジョウ, and the tree stays flexible.
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