What is 7 books in a series called?

Excuse me, but I'm curious to know something about literature. Specifically, I've come across a series of books that consists of seven volumes, and I'm wondering if there's a specific term used to describe such a collection. Is there a universally accepted name for a series of seven books that are interconnected or follow a common theme? I'm just trying to get a better understanding of the terminology used in this area. Thank you for your help.