1. (n.) The branch of philosophy studying the nature of reality, the relationship between mind and matter\; the science of real as distinguished from phenomenal being; ontology; also, the science of being, with reference to its abstract and universal conditions, as distinguished from the science of determined or concrete being; the science of the conceptions and relations which are necessarily implied as true of every kind of being; philosophy in general; first principles, or the science of first principles.

2. (n.) Hence: The scientific knowledge of mental phenomena; mental philosophy; psychology.

aesthetics axiology casuistry cosmology epistemology ethics existentialism first philosophy gnosiology hyperphysics logic mental philosophy moral philosophy ontology phenomenology philosophastry philosophic doctrine philosophic system philosophic theory philosophical inquiry philosophical speculation philosophy school of philosophy school of thought science of being sophistry the first philosophy theory of beauty theory of knowledge value theory