steam engine: 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: a heat engine in which ignition occurs outside the chamber (cylinder or turbine) in which heat is converted to mechanical energy
puffer: any of numerous marine fishes whose elongated spiny body can inflate itself with water or air to form a globe; several species contain a potent nerve poison; closely related to spiny puffers