metaphysics ontology http://id.loc.gov/authorities/subjects/sh85094833 https://en.wikipedia.org/wiki/Category:Ontology https://en.wikipedia.org/wiki/Ontology https://www.wikidata.org/wiki/Q44325 BD300-BD444 The branch of philosophy that studies concepts such as existence, being, becoming, and reality. It includes the questions of how entities are grouped into basic categories and which of these entities exist on the most fundamental level. Ontology is traditionally listed as a part of the major branch of philosophy known as metaphysics.