aching of limbs, muscular pains
疢 centers on deep, persistent bodily pain: aching limbs and muscular soreness.
疢 combines the sickness radical 疒 with 火, but the exact historical role of 火 is uncertain. It may have originally contributed a sound element or been a simplified form of a more complex component.
The sickness enclosure 疒 wraps around 火 (fire). Picture a feverish fire burning inside your limbs, causing aching and muscular pain.
For チン, imagine a chin-up bar causing aching muscles: chin -> チン, and the soreness spreads through your limbs.
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