thermomotor

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An engine operated by heat, especially by the expansion of heated air.

Century Dictionary and Cyclopedia

1. n. A heat-engine, particularly a so-called caloric engine, or an air-engine driven by the expansive force of heated air. Compare gas-engine, heat-engine, and caloric engine (under caloric).

GNU Webster's 1913

1. n. A heat engine; a hot-air engine.