An attribute that names or identifies entity instances is a(n):entity.attribute.identifier.relationship.

In the context of database design and entity-relationship modeling, the correct term for an attribute that names or identifies entity instances is typically referred to as an identifier. Identifiers play a crucial role in uniquely distinguishing between different instances of an entity within a dataset.

To summarize:

• An entity represents a real-world object or concept in a database.
• An attribute is a property or characteristic of an entity.
• An identifier is a specific type of attribute that uniquely identifies an instance of an entity, ensuring that each record can be distinctly referenced.

In conclusion, the complete statement would be: An attribute that names or identifies entity instances is a(n) identifier.