A Rude Awakening
It has bounced around as uncultured, ignorant, unrefined, uncivil, lacking in refinement, and downright primitive.
So it’s interesting to see that it shares a root with its polar opposite, erudite-- scholarly, well-instructed, intelligent. It is formed from the Latin e-, out or away from, and rudis, untrained, etc.
Also in the family is the word rudiments, the first basic things taught when a subject is first approached. The adjective form is rudimentary, which Sherlock Holmes could have used instead of “Elementary, my dear Watson.” [Yes, I know that the line came from a stage or movie version rather than from Conan Doyle himself, but it’s germane.]
Over the centuries, we have lost rudeful (full of rudeness), rudery (act of rudeness), rudesby (a rude fellow), rudeship (roughness), rudish (somewhat rude), and rudesse and rudity (rudeness).
(substitute @ for AT above)
It's here! McFarland & Co.: Word Parts Dictionary, 2nd edition