Nation (Noun)

1. a large body of people, associated with a particular territory, that is sufficiently conscious of its unity to seek or to possess a government peculiarly its own: The president spoke to the nation about the new tax. 2. the territory or country itself: the nations of Central America. 3. a member tribe of an American Indian confederation. 4. an aggregation of persons of the same ethnic family, often speaking the same language or cognate languages.
* Excerpted from the Random House Webster's Unabridged Dictionary 3.0.

It is interesting that the Wordsmyth Dictionary and Thesaurus on the Internet (apparently more cosmopolitan in its approach) offers the following definitions (and synonyms), in order:

1.   a people living in the same geographic region and having a common history, language, and culture.
     Synonyms: land , country , people , race , public
2.   a people living under its own independent government.
     Synonyms: country , state
3.   the members of a federation or tribe, esp. North American Indians.