This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
臅 combines ⺼ (meat/flesh) with 蜀, which likely contributes sound. The exact historical development is uncertain.
The left side ⺼ suggests flesh or body, and the right side 蜀 is a phonetic component. Without a clear meaning, picture a mysterious piece of meat labeled with the sound 'shoku'.
For ショク, imagine a shock of electricity hitting a piece of meat (⺼) on the right side 蜀: shock -> ショク.
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