1. The belief that all material objects are made up of matter, which is only potential, and form, which makes the object an actuality.
2. The theory that every physical object is composed of two principles, an unchanging prime matter and a form deprived of actuality with every substantial change of the object.
3. A metaphysical view according to which every natural body consists of two intrinsic principles, one potential (namely, primary matter) and one actual (namely, substantial form); the permanent principle is matter, the actual principle is form.