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English definition of “warn”

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warn

verb [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 give us a slight stomach upset. [+ 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. 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 and come over here, Laura - I'm warning you (= I will punish you if you do not)!
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(Definition of warn from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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