This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鱪 combines 魚 (fish) with 暑 (hot), likely created as a kokuji to name a specific fish associated with warm seasons or waters. The exact historical development is uncertain.
The left side is 魚 (fish) and the right side is 暑 (hot). Picture a fish that thrives in hot summer waters, but remember its standalone meaning is unclear.
For しいら, imagine a fish called 'Sheila' that loves hot weather: Sheila -> しいら, and the fish 魚 swims in the heat 暑.
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