The Collaborative International Dictionary
AEolipile \[AE]*ol"i*pile\, AEolipyle \[AE]*ol"i*pyle\, n. [L. aeolipilae; Aeolus god of the winds + pila a ball, or Gr. ? gate (i. e., doorway of [AE]olus); cf. F. ['e]olipyle.] An apparatus consisting chiefly of a closed vessel (as a globe or cylinder) with one or more projecting bent tubes, through which steam is made to pass from the vessel, causing it to revolve. [Written also eolipile.]
Note: Such an apparatus was first described by Hero of Alexandria about 200 years b. c. It has often been called the first steam engine.
Wiktionary
n. a steam engine powered by rocket propulsion due to escaping steam; which consists of a pressure vessel mounted on a bearing, with one or more tubes which exhaust steam tangentially to the rotation axis thus creating rotation.
Wikipedia
An aeolipile (or aeolipyle, or eolipile), also known as a Heron's engine, is a simple bladeless radial steam turbine which spins when the central water container is heated. Torque is produced by steam jets exiting the turbine, much like a tip jet or rocket engine. In the 1st century AD, Hero of Alexandria described the device, and many sources give him the credit for its invention.
The aeolipile Heron described is considered to be the first recorded steam engine or reaction steam turbine. The name – derived from the Greek word Αἴολος and Latin word pila – translates to "the ball of Aeolus", Aeolus being the Greek god of the air and wind.
Pre-dating Heron's writings, a device called an aeolipile was described in the 1st century BC by Vitruvius in his treatise De architectura; however, it is unclear whether it is the same device or a predecessor, as there is no mention of any rotating parts.
Usage examples of "aeolipile".
The aeolipile of Hero spun in the temple at Alexandria, hissing softly to itself and blowing jets of steam into the fire-lit dimness.
This had been something like the famous aeolipile of Hero-in a lost timeline, a manufacturer of mechanical novelties in Alexandria-just a pressure vessel with two canted nozzles that would vent steam and spin around like a lawn sprinkler.