insanity
noun [ U ] uk/ɪnˈsæn.ə.ti/ us/ɪnˈsæn.ə.t̬i/
精神错乱，精神失常
the condition of being seriously mentally ill
He was found not guilty of murder by reason of insanity. 他因为精神失常而未被判犯有杀人罪。
He suffered from periodic bouts of insanity. 他患有周期性精神失常。
疯狂;失去理智
an action that is stupid and likely to have extremely bad results
It would be insanity to expand the business now. 现在扩大经营规模简直是疯了。