This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
溳 combines the water radical 氵 with 員, which likely contributes sound. The exact historical development is uncertain.
Water 氵 beside 員 (member) could suggest a member of a water-related group, but the meaning is unclear. Picture a mysterious water spirit named 員.
For ウン, imagine an 'oon' sound echoing over water: oon -> ウン, like a deep water note.
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