du•al•ismˈdu əˌlɪz əm, ˈdyu-(n.)

1. the state of being dual or consisting of two parts; division into two.

2. (in metaphysics) any of various theories holding that reality is composed of two mutually irreducible substances. (in epistemology) the view that substances are either material or mental.

   Category: Philosphy

   Ref: Compare monism (def. 1a), 1 1 pluralism (def. 1a). 1 1

3. the theological doctrine that there are two eternal principles, one good and one evil. the belief that humans embody two parts, as body and soul.

   Category: Religion

Origin of dualism:

1785–95

du′al•ist(n.; adj.)