What is Aristocracy?

Legal Definition
Aristocracy (Greek ἀριστοκρατία aristokratía, from ἄριστος aristos "excellent," and κράτος kratos "power") is a form of government that places power in the hands of a small, privileged ruling class. The term derives from the Greek aristokratia, meaning "rule of the best".

At the time of the word's origins in Ancient Greece, the Greeks conceived it as rule by the best qualified citizens—and often contrasted it favourably with monarchy, rule by an individual. In later times, aristocracy was usually seen as rule by a privileged group, the aristocratic class, and was contrasted with democracy.
-- Wikipedia
Legal Definition
That form of government in which the sovereign power is exercised by a small number of persons to the exclusion of the remainder of the people.
-- Bouviers Law Dictionary
Legal Definition
A government in which a class of men rules supreme. A form of government which is lodged in a council composed of select members or ndbles, without a monarch, and exclusive of the people. A privileged class of the people; nobles and dignitaries; people of wealth and station.
-- Black's Law Dictionary
Legal Definition
A government ruled by a class.
-- Ballentine's Law Dictionary