This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
旵 combines 日 (sun) and 山 (mountain), but its exact historical development and original meaning are uncertain.
The sun 日 over a mountain 山 could suggest dawn or a bright landscape, but the kanji's actual meaning is unclear.
For タン, imagine the sun tanning the mountain: tan -> タン, with the sun 日 shining on the mountain 山.
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