Meaning of “warn” in the English Dictionary

british dictionary

"warn" in British English

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warnverb [ I or T ]

uk /wɔːn/ us /wɔːrn/

B1 to make someone realize a possible danger or problem, especially one in the future:

[ + obj + to infinitive ] We were warned not to eat the fish which might upset our stomachs.
[ + obj + (that) ] Have you warned them (that) there will be an extra person for dinner?
I was warned against/off going to the east coast because it was so full of tourists.
The boating area is marked with buoys to warn off swimmers.
There were signs warning of fog as soon as we got onto the motorway.
This particular curry is extremely hot - be warned!
Put that ball down now, Laura - I'm warning you (= I will punish you if you do not)!

More examples

  • I have to warn you that there's a degree of danger involved in this.
  • My sister warned me not to trust him.
  • I'm warning you, don't mess about with those tools.
  • The leaflet warns children about the dangers of smoking.
  • My mother always warned me not to talk to strangers.

(Definition of “warn” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)

"warn" in American English

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warnverb [ I/T ]

us /wɔrn/

to make someone aware of a possible danger or problem so that it can be avoided:

[ T ] I warned her not to waste her money on that movie.
[ T ] We’d been warned that we should lock our cars in the parking lot.
[ I ] The radio warned all day of the bad weather coming.

(Definition of “warn” from the Cambridge Academic Content Dictionary © Cambridge University Press)