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English definition of “insidious”


adjective    /ɪnˈsɪd·i·əs/
(of something unpleasant or dangerous) gradually and secretly causing harm: Cancer is an insidious disease. insidiously    /ɪnˈsɪd·i·əs·li/ adverb His negative attitude slowly and insidiously spoiled the atmosphere around the office.
(Definition of insidious adjective from the Cambridge Academic Content Dictionary © Cambridge University Press)
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