What term describes a field containing redundant data that links two or more tables in a relational database?

The correct term to describe a field containing redundant data that links two or more tables in a relational database is "Key." In the context of relational databases, a key serves as a unique identifier for records in a table. This often involves primary keys, which uniquely identify a record within a particular table, and foreign keys, which are fields in one table that reference primary keys in another table.

The presence of keys allows for the establishment of relationships between different tables, facilitating the organization and recovery of data. When a foreign key is a repetition of data that exists in separate tables, it essentially serves to create a connection that maintains relational integrity across the database. This redundancy is purposeful, as it allows databases to efficiently reference related data while preserving the ability to access each set of data independently.