Final answer:
A primary key formed from two or more columns in a table is known as a composite key, which serves as a unique identifier for table records.
Step-by-step explanation:
When more than one column in a table is combined to form a primary key, it is called a composite key. A composite key is a unique identifier for records in a table; it unifies two or more columns to create a single primary key. This is essential for maintaining the integrity of the database and ensuring that each record is uniquely identified by a combination of column values.