‘切记’ is a formal, emphatic verb meaning ‘to bear in mind firmly’ or ‘to remember well — and act accordingly.’ The character 切 (qiē) here means ‘urgent’ or ‘earnest,’ not its more common meaning of ‘to cut’; 记 (jì) means ‘to remember’ or ‘to keep in mind.’ Together, they form an expression that conveys strong urgency and seriousness — it’s not just casual remembering, but a committed mental note with implied responsibility to follow through.

This phrase is frequently used in instructions, warnings, advice, and public notices — especially where safety, etiquette, or important procedures are involved. It often appears at the beginning or end of a sentence for rhetorical emphasis, and is common in written Chinese (e.g., signs, manuals, teacher’s reminders) more than in casual speech. While grammatically a verb, it typically functions as an imperative or adverbial phrase, and is usually followed by a clause or infinitive-like verb phrase (e.g., 切记不要迟到).