Definition from Wiktionary, the free dictionary
dualism (plural dualisms)
- Duality; the condition of being double.
- (philosophy) The view that the world consists of, or is explicable in terms of, two fundamental principles, such as mind and matter or good and evil.
- (theology) The belief that the world is ruled by a pair of antagonistic forces, such as good and evil; the belief that man has two basic natures, the physical and the spiritual.
Related terms 
the view that the world consists of two fundamental principles
the belief that the world is ruled by a pair of antagonistic forces