ontology

noun

1. the branch of metaphysics that studies the nature of existence or being as such.
2. (loosely) metaphysics.

noun

1. philosophy the branch of metaphysics that deals with the nature of being
2. logic the set of entities presupposed by a theory

n.“metaphysical science or study of being,” 1660s (Gideon Harvey), from Modern Latin ontologia (c.1600), from onto- + -logy.