[self-propelling projectile] 1610s, "projectile consisting of a cylindrical tube of pasteboard filled with flammable or explosive matter," 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," Middle Dutch rokke, Old Norse rokkr), from Proto-Germanic *rukkon- (from PIE root *rug- "fabric, spun yarn").
Originally of fireworks rockets, the meaning "device propelled by a rocket engine" is recorded by 1919 (Goddard); rocket-ship in the space-travel sense is attested from 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, February 1927]