This criterion of demarcation between empirical and non-empirical theories I have also called the criterion of falsifiability or the criterion of refutability. It does not imply that irrefutable theories are false. Nor does it imply that they are meaningless. But it does imply that, as long as we cannot describe what a possible refutation of a certain theory would be like, that theory may be regarded as lying outside the field of empirical science.
The criterion of refutability or falsifiability may also be called the criterion of testability. For testing a theory, like testing a piece of machinery, means trying to fault it. Thus a theory that we know in advance cannot possibly be faulted or refuted is not testable.