warn

To tell someone about a danger or problem so they can avoid it or prepare.

• Please warn me if you see smoke.
• The guide warned us about falling rocks.
• Doctors have warned against drinking the water.

How to use it: warn someone about/of something (They warned us about the icy road.); warn someone not to do something (She warned me not to touch the hot pan.); warn that… (Experts warn that the storm could cause flooding.)

Similar words: alert, caution

Common phrases: warn someone, warn of danger, warn about something, warn against something

To tell someone their behavior is unacceptable and may lead to punishment.

• I warned him to stop shouting.
• The referee warned both players about their behavior.
• She has already been warned twice for breaking the rules.

How to use it: warn someone not to do something (The teacher warned us not to cheat.); warn someone that… (The manager warned him that another late arrival would cost him his job.)

Similar words: caution, admonish

Common phrases: warn someone, warn someone again, warn against cheating

To tell someone about something before it happens, so they know what to expect.

• Warn me before you arrive.
• I warned him that the parcel would be huge.
• She had warned us about the extra guests.

How to use it: warn someone that… (I warned her that we would arrive late.); warn someone about something (He warned us about his parents' planned visit.)

Similar words: tell, notify, inform

Common phrases: warn someone beforehand, warn someone in advance, warn about something

To formally tell someone they must attend a meeting or carry out a duty.

• The sheriff warned him to appear in court.
• Members were warned to attend the council meeting.
• The notice warned each juror to report on Monday.

How to use it: warn someone to do something (The officer warned him to appear before the court.); warn someone to a meeting (The clerk warned all members to the annual meeting.)

Similar words: summon, notify

Common phrases: warn someone to attend, warn someone to appear