An account of what kinds of things exist and how they relate. Where a taxonomy ranks, an ontology connects.
Greek ontos (being, that which is) + logia (study, discourse); the study of being and the nature of existence and relationships
A knowledge system table. The relationship graph connecting keywords through subject-predicate-object triples. Every piece of every relationship — subject, predicate, object, cardinality, source — is a keyword reference. The web of being itself.