Do you know ghouls from goblins and ghosts?
late 13c., "coarse, rough" (of surfaces), from Old French ruide (13c.) or directly from Latin rudis "rough, crude, unlearned," perhaps related to rudus "rubble." Sense of "ill-mannered, uncultured; uneducated, uncultured" is from mid-14c. Rude boy (also rudie, for short) in Jamaican slang is attested from 1967. Figurative phrase rude awakening is attested from 1895.