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English definition of “insane”

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insane

adjective uk   /ɪnˈseɪn/ us  
C2 mentally ill: For the last ten years of his life he was clinically insane. informal I sometimes think I'm going insane (= I feel very confused).C1 extremely unreasonable or stupid: It would be insane not to take advantage of this opportunity.

insane

noun [plural] uk   /ɪnˈseɪn/ us  
the insane mentally ill people: a hospital for the criminally insane
(Definition of insane from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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