pole
橦 centers on a long, straight wooden object: a pole. The meaning is concrete and specific, referring to a wooden shaft or post.
橦 combines 木 (tree/wood) with 童, which likely contributes the sound. The character originally referred to a type of tree or wooden pole.
The left side 木 is a tree, and the right side 童 looks like a child standing tall. Imagine a tall wooden pole made from a tree, like a child's height marker carved into a post.
For シュ, picture a shoe hanging from the top of a wooden pole: shoe -> シュ, and the pole holds it up.
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