| Rocketry. a projected type of propulsion for vehicles in outer space, the exhaust consisting of positive ions and negative electrons repelled from the vehicle by electrostatic forces, resulting in a very high exhaust velocity. |
| ionic propulsion n. Propulsion by the reactive thrust of a high-speed beam of similarly charged ions ejected by an ion engine. Also called ion propulsion. |
| ion propulsion n. See ionic propulsion. |