The Greek etymology of the word "autonomy" tells us that it is being a law unto itself -- not being governed by any superior on earth.
It is worth commenting here on a mistake we find in Rousseau's Social Contract. In a hypothetical state of nature, and so in the absence of society. Every human being has the freedom of autonomy. But when they enter freely into the social contract, Rousseau say they are still as autonomous as before.
No one in a political society is autonomous. The citizens who obey the laws in the making of which they have a voice enjoy political freedom, but political freedom is not the freedom of autonomy -- the freedom of people in a state of nature, rather it is to be governed with one's own consent and with a voice in one's own government.
What Rousseau calls "a state of nature" is not natural if the word "natural" is used in Rousseau's sense that refers to a hypothetical state of nature. Instead, it is both natural and conventional. It is natural by need; human beings need political society in order to live well; and at the same time it is conventional, not by a social contract, but rather as constituted by such men as Solon and Lycurgus, who respectively gave constitutions to Athens and to Sparta.
When this meaning is understood, certain passages in Aristotle's "Politics", Book I, chapter 2, which at first appear to be contradictory, become intelligible without contradiction. In other words, human beings cannot achieve a good or civilized life unless they are citizens of a state, but the states that are thus constituted differ conventionally from place to place.