the.com/propulsion module

means The section of a spacecraft that houses the engines, fuel, and thrusters responsible for getting it where it's going and keeping it pointed the right way.

from Built from Latin 'propellere' — pro- ('forward') plus pellere ('to drive or push') — the same root that gives us 'propel' and 'propeller.' 'Module' comes from Latin 'modulus,' a small measure, adopted in 20th-century engineering and especially the space program to mean a self-contained, swappable unit — think Apollo's lunar and command modules. Pair them and you get a 20th-century compound built for the Space Age: a discrete, bolt-on unit whose entire job is the pushing.