1. notify of danger, potential harm, or risk

- The director warned him that he might be fired

- The doctor warned me about the dangers of smoking

Definition categories: communication, inform

2. advise or counsel in terms of someone's behavior

- I warned him not to go too far

- I warn you against false assumptions

- She warned him to be quiet

Similar word(s): admonish, discourage, monish

Definition categories: communication, advise, counsel, rede

3. ask to go away

- The old man warned the children off his property

Definition categories: communication, enjoin, order, say, tell

4. notify, usually in advance

- I warned you that I would ask some difficult questions

Definition categories: communication, inform

Sentences with warn as a verb:

- We waved a flag to warn the oncoming traffic.

- He was warned against crossing the railway tracks at night.

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

- I phoned to warn him of the rail strike.