Metametaphysics is a branch of philosophy that explores the foundations of metaphysics.
"Metaphysics is concerned with the foundations of reality. It asks questions about the nature of the world, such as: Aside from concrete objects, are there also abstract objects like numbers and properties? Does every event have a cause? What is the nature of possibility and necessity? When do several things make up a single bigger thing? Do the past and future exist? And so on.
Metametaphysics is concerned with the foundations of metaphysics. It asks: Do the questions of metaphysics really have answers? If so, are these answers substantive or just a matter of how we use words? And what is the best procedure for arriving at them—common sense? Conceptual analysis? Or assessing competing hypotheses with quasi-scientific criteria?"[1]