Plain English Meaning
TAE was a company that built small aircraft engines that burn jet fuel instead of avgas, similar in principle to a car diesel engine. Their engines became a well-known option for light aircraft looking to use jet fuel.
Full Definition
Thielert Aircraft Engines (TAE) was a German manufacturer that developed certified diesel-cycle aircraft engines designed to run on jet fuel (Jet A) rather than aviation gasoline. Their Centurion series engines were installed in light aircraft such as the Diamond DA40 and DA42, and represented one of the first widely certified modern diesel powerplants for general aviation. The company's assets were later acquired and the engine line continued under the name Continental Diesel (now part of Continental Aerospace Technologies).