the said; the ... in question
Prefix used in formal or legal contexts to refer back to a previously mentioned item, person, or matter. Common in compounds like 該当, 該当者, 該当項目.
Please check the applicable item.
Those who are applicable, please come to the counter.
the relevant; the said; the appropriate
profound; extensive (knowledge)
the said proposal; the proposal in question
the said person; the person in question
the matter in question; the said problem
The kanji 該 originally means 'to be applicable' or 'to correspond to'. As a prefix, it is used in formal writing to refer to something previously mentioned. The reading がい is the on'yomi.