Ontology is the philosophical study of the nature of being, becoming, existence, or reality, as well as the basic categories of being and their relations. Traditionally listed as a part of the major branch of philosophy known as metaphysics, ontology often deals with questions concerning what entities exist or may be said to exist and how such entities may be grouped, related within a hierarchy, and subdivided according to similarities and differences. A very simple definition of ontology is that it is the examination of what is meant, in context, by the word 'thing'.
Source: https://en.wikipedia.org/wiki/Ontology
(✂︎ From the ongoing #JoDoesPhD words I googled this week series)