A political system in which the central government holds all legitimate power. The central government may delegate power of functional responsibilities to territorial units (often called departments, regions, or prefectures), but those delegated powers and functions can be r3voked at any time. Examples: China, France, Japan, United Kingdom.
A unitary state is a state or country that is governed constitutionally as one single unit, with one constitutionally created legislature. The political power of government in such states may well be transferred to lower levels, to regionally or locally elected assemblies, governors and mayors ("devolved government"), but the central government retains the principal right to recall such delegated power.