hastily, suddenly
倐 centers on sudden, swift action: doing something hastily or unexpectedly, often with a sense of urgency.
倐 is a rare character combining 攸 (a phonetic component suggesting swiftness) with 火 (fire), possibly reinforcing the idea of sudden, fleeting movement like a flame. The exact historical development is uncertain.
The outside 攸 suggests swift movement, and the inside 火 (fire) adds the image of a sudden blaze. Picture a fire flaring up hastily and unexpectedly.
For シュク, imagine a sudden shock (ショック) that makes you act hastily: shock -> シュク, and the fire inside 倐 flares up in an instant.
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