meandering, serpentine
蜒 centers on winding, twisting movement like a snake or a curving path: meandering or serpentine.
蜒 combines 虫 (insect/reptile) with 延 (extend/prolong), suggesting a creature that extends itself in a winding manner. The exact historical development is uncertain, but the phono-semantic structure is plausible.
A bug (虫) that extends (延) its body in curves: picture a caterpillar or snake inching along, creating a meandering, serpentine path.
For エン, imagine an endless (エン) serpentine line drawn by a meandering bug: endless -> エン.
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