propellant (n.)youdaoicibaDictYouDict
less-etymological, but more usual, spelling of propellent; 1881 as a firearm explosive; 1919 as "fuel for a rocket engine."
rocket (n.2)youdaoicibaDictYouDict
type of self-propelling projectile, 1610s, from Italian rocchetto "a rocket," literally "a bobbin," diminutive of rocca "a distaff," so called because of cylindrical shape. The Italian word probably is from a Germanic source (compare Old High German rocko "distaff," Old Norse rokkr), from Proto-Germanic *rukkon-, from PIE root *rug- "fabric, spun yarn."

Originally "fireworks rocket," meaning "device propelled by a rocket engine" first recorded 1919; rocket-ship in the modern sense first attested February 1927 ("Popular Science"); earlier as a type of naval warship firing projectiles. Rocket science in the figurative sense of "difficult, complex process or topic" is attested by 1985. Rocket scientist is from 1952.
That such a feat is considered within the range of possibility is evidenced by the activities of scientists in Europe as well as in America. Two of them, Prof. Herman Oberth and Dr. Franz Hoeff, of Vienna, are constructing a five-ton rocket ship in which they hope to reach the moon in two days. ["Popular Science," Feb. 1927]
thruster (n.)youdaoicibaDictYouDict
type of rocket engine, 1962, agent noun; see thrust (n.).
ablatoryoudaoicibaDictYouDict
" Astronautics and Materials Sci. A protective surface layer (e.g. in a rocket engine) made of a material which ablates readily when heated and so reduces the transfer of external heat to the underlying material", Mid 19th cent.; earliest use found in Jeremy Bentham (1748–1832), philosopher, jurist, and reformer. From ablate + -or.