Psychopathy (sai · kaa · puh · thee) is a common mental disorder. It is characterized by personality traits that include reduced empathy and remorse, a bold and daring personality, and difficulty inhibiting behaviors.
People with psychopathy may deceive, manipulate, exploit, threaten, steal from, or physically harm others. At the same time, they may seem outwardly friendly and well adjusted. This ‘mask of sanity,’ described in the quote above, can make psychopathic people very hard to identify.