P&W R-2800 supercharged or turbocharged in the Hellcat?

[Nypsy]

I was sure in its application in the Hellcat the R-2800 was turbocharged but I can find no references to confirm that.
Some sources describe it as being turbo-supercharged. 

[Cthulhu]

Supercharged

[Kenne]

for fighters I believe only the 47 n 38 had turbos...

 

[MiloMorai]

XF6F-2 (66244), an F6F-3 converted to use a Wright R-2600-15, fitted with a Birman manufactured mixed-flow turbocharger, which was later replaced by a Pratt & Whitney R-2800-21, also fitted with a Birman turbocharger.[31] The turbochargers proved to be unreliable on both engines, while performance improvements were marginal.

[smoe]

This sums it up a bit:

Turbochargers were originally known as turbosuperchargers when all forced induction devices were classified as superchargers. Nowadays the term "supercharger" is usually applied to only mechanically driven forced induction devices.[4] The key difference between a turbocharger and a conventional supercharger is that the latter is mechanically driven by the engine, often through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by the engine's exhaust gas. Compared to a mechanically driven supercharger, turbochargers tend to be more efficient, but less responsive. Twincharger refers to an engine with both a supercharger and a turbocharger.

Source: http://en.wikipedia.org/wiki/Turbocharger