psychopath

psychopath
/ˈsaɪkəupæθ; `saɪkəˌpæθ/ n
person suffering from a severe mental or emotional disorder,esp one who behaves in a violently aggressive or antisocialway 精神变态者, 精神病患者（尤指行为有破坏性或危害社会者）.

牛津英汉双解词典