1) Interloper 2) Intruder 3) Maneuvering rocket 4) Pusher 5) Rocket power source 6) Small rocket 7) Spacecraft attachment 8) Spacecraft part 9) Trespasser 1) Pusher 
A thruster is a propulsive device used by spacecraft and watercraft for station keeping, attitude control, in the reaction control system, or long-duration, low-thrust acceleration. ==Spacecraft thrusters== ==Marine thrusters== ==Others== ...
• (n.) One who thrusts or stabs.
Rocket engines used for maneuvering spacecraft in space.
A small rocket used by a spacecraft to control or change its attitude.
a device generating a small thrust by the ejection of matter for adjusting the attitude, the state of rotation, or the orbit, including the position in orbit, of a spacecraft
Thrust'er noun One who thrusts or stabs. 
an engine on a spacecraft or aircraft that controls in what direction and how high it flies
Thruster is hunting slang for a rider who rides ahead of the group close to the hounds.
[n] - a small rocket engine that provides the thrust needed to maneuver a spacecraft
noun one who intrudes or pushes himself forward noun a small rocket engine that provides the thrust needed to maneuver a spacecraft