typedef longUnderstandableName sn;
Then you can define the methods as
void sn::MethodA() {}
void sn::MethodB() {}
and use them as
sn::MethodA();
sn::MethodB();
This only works if longUnderstandableName is the name of a class. It works even if the class is deeply embedded in some other namespace.
If longUnderstandableName is the name of a namespace, then in the namespace (or source file) where you want to use the methods, you can write
using namespace longUnderstandableName;
and then call methods like
MethodA();
MethodB();
You should be careful not to use a using namespace foo; in header files, because then it pollutes every .cpp file that we #include the header file into, however using a using namespace foo; at the top of a .cpp file is definitely allowed and encouraged.