This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
誋 combines 言 (speech) with 忌, which likely contributes the sound. The exact historical development is uncertain.
With 言 (speech) and 忌 (mourning/abhorrence), imagine words spoken in warning or prohibition, but the exact meaning is uncertain.
For キ, imagine a key (キー) that locks away forbidden speech: key -> キ, and the words are sealed.