favus, scabies
鬎 centers on skin diseases that cause crusty or itchy lesions, specifically favus (a fungal scalp infection) and scabies (a mite infestation). Both meanings share the idea of a visible, uncomfortable skin condition.
鬎 combines 髟 (hair) with 剌, which likely contributes the sound and may relate to cutting or piercing, possibly referencing the crusty or burrowing nature of the skin conditions. The exact historical development is uncertain.
The top part 髟 suggests hair, and the bottom 剌 looks like a sharp tool cutting into skin. Picture a scalp condition where crusty patches form under the hair, like something burrowing and cutting.
For ラツ, imagine a rat (ラット) with scabies, scratching its crusty skin: rat -> ラツ, and the rat's discomfort matches the skin disease meaning.
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