warn

/wɔːn/

To make (someone) aware of (something impending); especially:

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

Don't let me catch you running in the corridor again, I warn you.

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

A sign warns trespassers off/away from the site.

To give warning.