the hanging flap in front of hat
綖 refers specifically to the hanging flap or ornamental front piece of a traditional hat. Its meaning is narrow and concrete, tied to historical headwear.
綖 combines 糸 (thread/silk) with 延 (extend), suggesting a silk piece that extends or hangs down. The exact historical development is uncertain, but the component relationship is plausible.
The left side 糸 is thread or fabric, and the right side 延 means extend. Picture a silk flap extending down from the front of a hat.
For エン, imagine the end of the hanging flap swaying in the wind: end -> エン, and the silk flap extends from the hat.
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