The domain of discourse, sometimes called the universe of discourse, logical discourse, or simply discourse, is an analytic tool used in deductive logic, especially predicate logic. It indicates the relevant set of entities that are being dealt with by quantifiers.
The term "universe of discourse" generally refers to the entire set of terms used in a specific discourse, i.e. the family of linguistic or semantic terms that are specific to any one area of interest. In model-theoretical semantics, the term "universe of discourse" refers to the set of entities that a model is based on.
A database is a model of some aspect of the reality of an organisation. It is conventional to call this reality the "universe of discourse" or "domain of discourse".