This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
曮 combines 日 (sun) with 嚴, which likely contributes the sound. The exact historical development and original meaning are uncertain.
The sun 日 beside the imposing 嚴 might suggest a harsh, glaring sunlight, but the true meaning is unclear.
For ガン, imagine the sun glaring down like a strict guard (ガン) beside the stern 嚴 component.
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