Metamathematics is another word for proof theory.
The branch of logic dealing with the study of the combination and application of mathematical symbols is also sometimes called metamathematics or metalogic.
Metamathematics
See also
Proof TheoryExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Metamathematics." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Metamathematics.html