PSYCHOPATH
sociopath, psychopath
(noun) someone with a sociopathic personality; a person with an antisocial personality disorder (‘psychopath’ was once widely used but has now been superseded by ‘sociopath’)
Source: WordNet® 3.1
Etymology
Noun
psychopath (plural psychopaths)
A person with a personality disorder indicated by a pattern of lying, cunning, manipulating, glibness, exploiting, heedlessness, arrogance, delusions of grandeur, sexual promiscuity, low self-control, disregard for morality, lack of acceptance of responsibility, callousness, and lack of empathy and remorse. Such an individual may be especially prone to violent and criminal offenses.
(figurative) A person with no moral conscience who perpetrates especially gruesome or bizarre violent acts.
A person diagnosed with antisocial or dissocial personality disorder.
(obsolete) A person diagnosed with any mental disorder.
Synonyms
• sociopath
Source: Wiktionary