1. According to those who distinguish ontology from other branches of metaphysics, ontology is the division of metaphysics that studies being as being, prescinding from its causes. Thus defined, it is also called general metaphysics.  Such a separated notion of metaphysics is the product of modern-rationalist divisions of the philosophical sciences and does not represent the classic Aristotelian or scholastic understanding of metaphysics. 2. A synonym for metaphysics. 3. The study of the fundamental aspects of things in general or of some particular domain of reality.