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English definition of “not”

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not

adverb uk   /nɒt/ us    /nɑːt/
A1 used to form a negative phrase after verbs like "be", "can", "have", "will", "must", etc., usually used in the short form "n't" in speech: He's not fat! I won't tell her. I can't go. Don't you like her? It isn't hard (= it is easy). I'm just not interested. He's not bad-looking (= he is fairly attractive). He's not as tall as his father.A1 used to give the next word or group of words a negative meaning: I told you not to do that. I like most vegetables but not cabbage. "Come and play, Dad." "Not now, Jamie." It was Yuko who said that, not Richard.A2 used after verbs like "be afraid", "hope", "suspect", etc. in short, negative replies: "Is he coming with us?" "I hope not." "Are you done?" "I'm afraid not."if not A2 used to say what the situation will be if something does not happen: I hope to see you there but, if not, I'll call you.or not A2 used to express the possibility that something might not happen: Are you going to reply or not? I still don't know whether she's coming or not. humorous sometimes used at the end of a statement to show that you did not mean what you have said: That was the best meal I've ever had - not!
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(Definition of not from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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