Ontological

relating to or based upon being or existence (Merriam-Webster) OR
 * Ontology** (from the [|Greek] ὄν, genitive ὄντος: "of being" (neuter participle of εἶναι: "to be") and [|-λογία], [|-logia]: //science//, //study//, //theory//) is the [|philosophical] study of the nature of //[|being], [|existence]// or //[|reality] in general//, as well as the basic [|categories of being] and their relations. (Wikipedia)