naive, guileless, simple-minded
悾 centers on a lack of worldly cunning: being naive, guileless, or simple-minded in a way that suggests innocence rather than cleverness.
悾 combines the heart radical 忄 with 空, which likely contributes the sound. The meaning likely derives from the idea of an empty or unburdened heart, suggesting simplicity or naivety.
The heart radical 忄 beside 空 (empty) suggests a heart that is empty of cunning or deceit: a naive, simple-minded person.
For コウ, imagine a naive person with an empty heart walking into a kō (こう) meeting, completely unaware of the formalities: kō -> コウ.
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