The question here is what is signified by the lexical token 'theory' in String Theory.
It's something of a rhetorical question because it is, I think, used in a special sense by physicists; for example we have also Chern-Simon Theories or Topological Quantum Field Theories - and these are far from actual physical theories in the sense that a scientifically orientated layman ie without a specialist knowledge of mathematical physics might think of them; this is sometimes acknowledged by the term toy theory ie not a physically appropriate one; and should be compared with, for example, well-established terms such as Newtons Theory of Gravity, or Einsteins Theory of General Relativity.
Here, the theories are buttressed by a complex not only of theoretical standing, but also empirical - ie the falsification criteria of Popper.
But then, it's easy to get confused between how the word theory is used; this suggests that there ought to be a kind of typology of the word theory signifying just how it is used.
One attempt in this direction appears to be the qualifier 'effective'; which suggests that a theory says nothing directly about the ontological status of the notions under consideration, but only that its modelling of physical phenomena is 'effective'.
Has there been any serious work done on distinguishing or characterising how this word is being used by the community in question?