Make someone aware of impending danger, evil, etc., notify or inform someone about something, summon someone to or inform them of a formal meeting or duty, and possibly make a sound indicating that a clock is about to strike or chime.

(transitive) To caution or admonish (someone) against unwise or unacceptable behaviour.

(chiefly with "off", "away", and similar words) To advise or order to go or stay away.

(intransitive) To give warning.