A multinational state or a multinational union is a sovereign entity that comprises two or more nations or states. This contrasts with a nation state, where a single nation accounts for the bulk of the population. Depending on the definition of "nation", a multinational state is usually multicultural or multilingual, and is geographically composed of more than one country, such as the countries of the United Kingdom.

A state is a political entity that regulates society and the population within a territory. Government is considered to form the fundamental apparatus of contemporary states.