from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A supercharger that uses an exhaust-driven turbine to maintain air-intake pressure especially in high-altitude aircraft. Also called turbocharger.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a turbocharger, an exhaust-powered turbine used to power increased air intake to an internal combustion engine ; an exhaust-turbine powered (in place of engine-powered) supercharger.
- n. a twincharger, combination of a supercharger and a turbocharger.
turbo- + supercharger (Wiktionary)
Logically then, adding a turbine to turn the supercharger would yield a "turbosupercharger".