a type of reaction-propulsion engine to propel rockets in space; a stream of positive ions is accelerated to a high velocity by an electric field
motor that converts thermal energy to mechanical work
something used to achieve a purpose
a wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks
an instrument or machine that is used in warfare, such as a battering ram, catapult, artillery piece, etc.
a particle that is electrically charged (positive or negative); an atom or molecule or group that has lost or gained one or more electrons