This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
蚴 combines 虫 (insect) with 幼 (young), but the exact historical development and original meaning are uncertain.
The left side 虫 suggests an insect, and the right side 幼 suggests something young or immature. Picture a young insect, but remember the meaning is uncertain.
For ユウ, imagine a young insect saying 'you' as it points at you: you -> ユウ, tying the young insect shape to the reading.
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