bent tree, broken tree
柆 centers on a tree that is not straight or whole: a bent or broken tree. The meanings are closely related, describing a tree in a damaged or misshapen state.
柆 combines 木 (tree) with 立 (stand), but the exact historical origin is uncertain. It may have originally depicted a tree that stands in a bent or broken manner, though this is speculative.
A tree 木 that is forced to stand 立 under a heavy weight, causing it to bend or break. Picture a young sapling bent over by a large rock, its trunk cracked.
For ロウ, imagine a low, bent tree that grows crookedly near the ground: low -> ロウ, and the tree's shape matches its name.
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