I do not think anyone with even a small amount of C++ experience will be confused when 'STL' is referenced in the context of C++.
Of course it might be that every C++ developer i've interacted with doesn't really know the language very well. But considering the popular axiom that says something along the lines of 'people who claim they know C++ do not really know C++ while people who know C++ do not claim they know C++' what you wrote might actually be true :-P.