External-combustion engine and Steam engine

External-combustion engine noun - A heat engine in which ignition occurs outside the chamber (cylinder or turbine) in which heat is converted to mechanical energy.

Steam engine and external-combustion engine are semantically related. In some cases you can replace phrase "Steam engine" with "External-combustion engine", this phrases are similar.

Steam engine noun - External-combustion engine in which heat is used to raise steam which either turns a turbine or forces a piston to move up and down in a cylinder.

External-combustion engine and steam engine are semantically related. You can use "External-combustion engine" instead a noun phrase "Steam engine".