The kanji 該 (がい) primarily conveys the meaning of "that," "the," or "the aforementioned." It often indicates something that has already been specified or is relevant to the current context. It can also imply "corresponding to," "being applicable to," or "relevant."

・On-yomi (音読み): ガイ ・Kun-yomi (訓読み): None, or rarely used as a standalone verb

⚫︎ 該当者 Translation: The relevant person; the person in question ⚫︎ 当該事件 Translation: The case in question; the said incident ⚫︎ 該当する Translation: To correspond to; to be applicable to

The kanji 該 (がい) is a phono-semantic compound. It is composed of the radical 言 (げん, "word," "speech") on the left and 亥 (がい, "boar," the twelfth sign of the Chinese zodiac) on the right, which acts phonetically. The combination suggests the idea of "a word/statement/topic that is specifically pointed out." Initially, the character might have been associated with a specific address or reference, with the core meaning of "pointing to something." Over time, the meaning evolved towards "that," "the," or "aforementioned" as it is known today.