1 a the highest class in society; the nobility. b the nobility as a ruling class.
2 a government by the nobility or a privileged group. b a State governed in this way.
3 (often foll. by of) the best representatives or upper echelons (aristocracy of intellect; aristocracy of labour).
Etymology: F aristocratie f. Gk aristokratia f. aristos best + kratia (as -CRACY)
Useful english dictionary. 2012.