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English definition of “lunatic”

lunatic

noun [C] uk   /ˈluː.nə.tɪk/ us    /-t̬ɪk/
someone who behaves in a silly or dangerous way: He drives like a lunatic.Of unsound mindStupid and silly offensive old-fashioned a person who is mentally illOf unsound mindStupid and silly

lunatic

adjective uk   /ˈluː.nə.tɪk/ us    /-t̬ɪk/
silly in a dangerous wayOf unsound mindStupid and silly
(Definition of lunatic from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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