WordNet (r) 3.0 (2006):

psychopath
    n 1: someone with a sociopathic personality; a person with an
         antisocial personality disorder (`psychopath' was once
         widely used but has now been superseded by `sociopath')
         [syn: sociopath, psychopath]

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "psychopath":
   alcoholic, alternating personality, antisocial personality,
   catatoniac, certifiable case, disordered personality,
   disturbed personality, double personality, drug user,
   dual personality, emotionally unstable personality, escapist,
   hostile personality, hypochondriac, hypochondriast, idiot,
   imaginary invalid, immature personality, inadequate personality,
   inferior personality, malade imaginaire, maladjusted personality,
   manic-depressive, mental, mental case,
   mentally defective personality, moral insanity,
   multiple personality, neuropath, neurotic, neurotic personality,
   paranoiac, paranoid, paranoid personality, perverse personality,
   psycho, psychoneurotic, psychopathic case,
   psychopathic personality, psychotic, psychotic personality, schiz,
   schizo, schizoid, schizoid personality, schizophrenic, schizy,
   seclusive personality, sexual psychopath, shut-in personality,
   sociopath, split personality, valetudinarian, valetudinary,
   weak personality