The Collaborative International Dictionary of English v.0.48:

Psychopathy \Psy*chop"a*thy\, n. [Psycho- + Gr. ?, ?.] (Med.)
   Mental disease. See Psychosis, 2. -- Psy`cho*path"ic, a.
   -- Psy*chop"a*thist, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

psychopathic
    adj 1: suffering from an undiagnosed mental disorder [syn:
           psychopathic, psychopathologic, psychopathological]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "psychopathic":
   brain-damaged, brain-injured, catatonic, certifiable, disturbed,
   functional, manic-depressive, mentally ill, mentally sick,
   neuropsychiatric, neurotic, paranoiac, paranoid, psychiatric,
   psychobiological, psychodynamic, psychogenic, psychological,
   psychoneurological, psychopathological, psychophysical,
   psychophysiological, psychosexual, psychosocial, psychosomatic,
   psychotic, schiz, schizoid, schizophrenic, schizy