steam engine

noun

an engine worked by steam, typically one in which a sliding piston in a cylinder is moved by the expansive action of the steam generated in a boiler.

Origin of steam engine

First recorded in 1745–55

Related formssteam-en·gine, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

1751; earlier in the same sense was fire engine, atmospheric engine.

steam engine in Science

An engine in which the energy of hot steam is converted into mechanical power, especially an engine in which the force of expanding steam is used to drive one or more pistons. The source of the steam is typically external to the part of the machine that converts the steam energy into mechanical energy. Compare internal-combustion engine.