above-stated, the said, that specific
該 centers on pointing to something already mentioned or specific: the above-stated item, the said thing, or that particular one. It marks a definite reference rather than introducing new information.
該 combines 言 (speech, words) with 亥, which likely contributes the sound. The character originally meant to include or cover, and later developed the sense of referring to something previously stated.
Words (言) beside 亥: imagine a speaker pointing to a specific item on a list and saying 'that one'—the said thing is marked by the word.
For ガイ, picture a guide pointing to the above-stated item on a sign: guide -> ガイ, and the guide's words refer to that specific thing.
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corresponding to; being applicable to; being relevant to; coming under; falling under; fulfilling (requirements); meeting (conditions); qualifying for
appropriate (e.g. authorities); concerned; relevant; said; aforementioned; competent; applicable; respective
said; matter in question
the appropriate person; competent person
proper authorities; authorities concerned
stored message summary; MS
profundity; extensive (knowledge)
profound knowledge
the matter in question; the said problem
not applicable; n/a
relevant items; applicable items
person concerned; person qualified; person in question; party; litigant (legal)
the said proposal
the said person; the target (person)