speak ill of, vilify, berate, interrogate
誶 centers on hostile speech: speaking ill of someone, vilifying, berating, or harshly interrogating. The common thread is using words to attack or pressure another person.
誶 combines 言 (speech) with 卒, which likely contributes the sound and may suggest abrupt or forceful action, fitting the idea of harsh speech. The exact historical development of the compound is uncertain.
Words (言) that feel like a sudden, harsh attack (卒 can suggest a soldier or abrupt end) — imagine someone berating or interrogating you with sharp, cutting speech.
For スイ, picture a swift, harsh interrogation: the interrogator's words come at you like a sudden 'swish' of a blade — 'swish' cues スイ.