Untyped in this case means unityped, that is, everything has a single type! The purpose of static types is to catch type errors at compile time. If everything

Untyped in this case means unityped, that is, everything has a single type! The purpose of static types is to catch type errors at compile time. If everything has a single type and all operations receive and return objects of this type, no type error is caught at compile time. Other people mentioned that you can, indeed, implement geometric algebra operations with a family of types (for example, a type for lines, a type for planes, etc) rather than having a single type. And thus, operations like adding a scalar to a <something> return a type that isn't neither scalar nor <something>. Which will lead to a type error somewhere, hopefully!