Warn: notify of danger, potential harm, or risk; admonish or counsel in terms of someone's behavior; notify, usually in advance.
Synonym: caution, advise, inform, notify, call, summon, apprise, forewarn.
Example: The doctor warned me about the dangers of smoking.
Usage in Sentence: Warn of, not about.
Don’t say: They were warned about the danger.
ü Say: They were warned of the danger.