Definition of: eolipile

(ē·ol′ə·pīl) noun
1. A reaction engine consisting of a hollow sphere upon trunnions, usually above a boiler connected with it. At right angles to its trunnions, two or more radial pipes project from the sphere, their openings so disposed that the forcible ejection of steam rotates the sphere in the opposite direction.
2. One of various devices working on the same principle, as for operating toys, etc. Also e·ol′o·pile: often spelled aeol– or –pyle. [<L aeolipilae an instrument for investigating the nature of the wind <Aeolus god of the winds + pila a ball]
EOLIPILE