Final answer:
The statement is false. A 'nation' refers to a group of people with a common cultural heritage, while a 'state' is an organized political unit. A 'nation-state' is a political entity with a government that represents a culturally homogeneous population.
Step-by-step explanation:
The assertion that the term nation once referred exclusively to an ethnic group but now refers to a centralized political unit, or a state, is false. Historically, a nation has been associated with a group of people sharing common cultural elements, such as language, history, and traditions, while a state refers to the government and the institutional frameworks necessary for a society to function, including the establishment of laws, collection of taxes, and maintenance of order.
When the ideas of nation and state are combined, we get a nation-state, a concept describing a political entity where a majority of the inhabitants share a common culture or ethnicity, and also govern themselves through their own sovereign state. This can be seen, for example, in places like Japan, where the government and the majority of the population share a distinct cultural identity.
Furthermore, the term nation differs from terms such as country, state, or nation-state, each of which has specific connotations. A nation emphasizes cultural and ethnic commonalities, whereas a state focuses on political and administrative structures, a country describes a geographic territory with a sovereign government, and a nation-state combines these aspects, representing a political unit where government and culture coincide.