- an internal-combustion rotary engine that utilizes a triangular rotor that revolves in a chamber (rather than a conventional piston that moves up and down in a cylinder): it has fewer moving parts and is generally smaller and lighter for a given horsepower.
- a type of four-stroke internal-combustion engine without reciprocating parts. It consists of one or more approximately elliptical combustion chambers within which a curved triangular-shaped piston rotates, by the explosion of compressed gas, dividing the combustion chamber into three gastight sections
