Variant of monarchy; a system of government in which two individuals, the diarchs, are the heads of state. In most diarchies, the diarchs hold their position for life and pass the responsibilities and power of the position to their children or family when they die. Diarchy is one of the oldest forms of government. In modern usage diarchy means a system of dual rule, whether this be of a government or of an organisation. Such 'diarchies' are not hereditary.