A schematic of the entire database that describes the relationships in a database is called a(n):

An entity-relationship diagram (ERD) is a visual representation used to illustrate the relationships between entities within a database. This diagram helps in mapping out the various components of a database, such as tables or entities, their attributes, and the relationships that connect them. It serves as a blueprint for how data is organized and how different parts interact, which is essential for database design and management.

ERDs are particularly valuable during the initial phases of database design, as they allow designers to explore and establish the logical structure of the data without getting into the specifics of the implementation. This helps ensure that all necessary entities are covered and that the relationships between them are clearly defined.

In contrast, a data dictionary provides a detailed description of each element within the database but does not visually represent the relationships. An intersection relationship diagram and a data definition diagram are less commonly referenced terms in the context of database design, further highlighting that the entity-relationship diagram is the recognized standard for representing database relationships comprehensively.