- An engine that develops thrust by ejecting a jet, especially a jet of gaseous combustion products.喷气式发动机：一种用喷射流体来产生推进力的发动机，尤其指燃烧气体的喷气式发动机
- An engine that obtains the oxygen needed from the atmosphere, used especially to propel aircraft and distinguished from rocket engines having self-contained fuel-oxidizer systems.无内含供氧系统的发动机：一种从空气中获得所需氧气的发动机，尤用于推进飞机飞行，并以拥有自带燃料氧化系统区别于火箭发动机