Bourgeoisie is a beautiful word which today describes the capitalist class in Marxism, but originally referred to the wealthier members of the Third Estate in pre-revolution France. The modern definition came about in 1886 from Marx's writings, but the "Third Estate" meaning was first used in English in 1707. At some unknown point, the French word developed from Anglo-Norman burgeis, which meant "town-dweller". That's from Old French borjois, the root being borc, or "town". In Proto-Germanic, that was burgz, meaning "fortress" (and the etymon of the toponym suffix -burg), and in Proto-Indo-European, it was brg, which was used to described fortified areas. Usage of the word bourgeoisie has declined sharply since a peak in 1983, paralleling the fall of communism pretty well.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.