aristocracy n.

1560s, "government by those who are the best citizens," from French aristocracie (Modern French aristocratie), from Late Latin aristocratia, from Greek aristokratia "government or rule of the best; an aristocracy," from aristos "best of its kind, noblest, bravest, most virtuous" (see aristo-) + abstract noun from kratos "rule, power" (see -cracy).

In early use contrasted with monarchy; after the French and American revolutions, with democracy. The meaning "rule by a privileged class, oligarchy, government by those distinguished by rank and wealth" (best-born or best-favored by fortune) is from 1570s and became paramount 17c. Hence, the meaning "patrician order, the of hereditary nobles" (1610s) and, generally, "persons notably superior in any way, taken collectively" (1650s).