1. the scientific study of mental disorders, including their theoretical underpinnings, etiology, progression, symptomatology, diagnosis, and treatment. This broad discipline draws on research from numerous areas, such as psychology, biochemistry, pharmacology, psychiatry, neurology, and endocrinology. The term in this sense is sometimes used synonymously with abnormal psychology.

2. the behavioral or cognitive manifestations of such disorders. The term in this sense is sometimes considered synonymous with mental disorder itself. —psychopathological adj. —psychopathologist n.