Final answer:
Ad hoc queries are performed on an as-needed basis and are not predefined in OLAP. They allow users to directly access and analyze data based on their specific needs and questions.
Step-by-step explanation:
The term used to describe queries that are performed on an as-needed basis and are not predefined in OLAP is ad hoc queries. Ad hoc queries allow users to directly access and analyze data based on their specific needs and questions. These queries are flexible and can be created on the spot, providing quick and customized insights.