This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 誟 is uncertain. It visually combines 言 (speech) with 孝 (filial piety), but the original meaning and component relationship are unclear.
The left side is 言 (speech) and the right side is 孝 (filial piety). Without a clear meaning, picture a rare, forgotten word about respectful speech.
For コウ, use the reading of the right-side component 孝 (コウ). Imagine a child (子) speaking (言) with filial respect: 孝 -> コウ.
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