vomit
衉 centers on the act of vomiting, specifically the expulsion of stomach contents through the mouth.
衉 combines 血 (blood) with 各, which likely provides the sound. The character is associated with vomiting, possibly through the idea of blood or bodily fluid being expelled.
The left side is 血 (blood) and the right side is 各 (each). Imagine each time you vomit, you see a little blood—a vivid reminder that 衉 means vomit.
For カク, picture each (各) time you vomit, you cough (カク) up something unpleasant: cough -> カク, tying the sound to the act.
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