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English definition of “mad”

mad

adjective (SILLY)    /mæd/ (madder or maddest) mainly UK informal (US usually crazy)
B1 extremely silly or stupid: [+ to infinitive] You're mad to walk home alone at this time of night. He must be mad spending all that money on a coat. Some of the things she does are completely mad. → See also madcapStupid and sillyOf unsound mind
(Definition of mad adjective (SILLY) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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