Which term refers to the relations that are actually defined within a database?

The term that refers to the relations that are actually defined within a database is base tables. Base tables are the fundamental building blocks of a database schema, wherein each base table corresponds directly to a certain type of entity or object within the database. These tables consist of rows and columns, where each row represents a unique record and each column represents an attribute of that record.

Base tables store persistent data and do not depend on any other representations, which means they directly hold the actual data that is manipulated, queried, and altered within the database system. This is in contrast to other concepts such as views or virtual tables, which are derived from base tables but do not store data themselves; rather, they present data in a different way based on the underlying base tables.

Understanding the distinction between base tables and other types of tables is crucial for database design, as it helps in organizing data effectively and ensuring data integrity within the database environment.