ontology
Ontology (noun) means the area of philosophy that looks at what it means for something to exist.
Etymology
A learned borrowing from New Latin ontologia (1606, Ogdoas Scholastica, by Jacob Lorhard (Lorhardus)), from Ancient Greek ὤν, ὄντος (ṓn, óntos, 'being'), the present participle of εἰμί (eimí, 'being, existing, essence'), combined with λόγος (lógos, 'account'). By surface analysis it is onto- + -logy. Its first known use in English was in 1663, in Archelogia philosophica nova; or, New principles of Philosophy. Containing Philosophy in general, Metaphysicks or Ontology, Dynamilogy or a Discourse of Power, Religio Philosophi or Natural Theology, Physicks or Natural philosophy, by Gideon Harvey (1636–1702), London, Thomson, 1663. It was popularized as a philosophical term by the German philosopher Christian Wolff (1679–1754).