Anarchy (from Greek word anarkhos) means the absence of government or other political authority. It may denote a situation where in a country the political authority has been overthrown and no other faction is able to exert power over the country, thus falling in to an chaotic state. Also, anarchy may mean the hypothetical instance that the government is abolished and a new system is set up without a political authority necessary, as advocated by anarchists, or the absence of government in a primitive society which has not developed it.
For the ideology opposing the existence of government, see the article on anarchism.