sovereign state
A governmental organization with a defined territory on which it exercises internal and external sovereignty, a permanent population, a government, and the capacity to enter into relations with other sovereign states.
Per Wikipedia, the word 'nation' does not always refer to soverign states. For example, the "nation of Islam".
William R. Hogan
de facto sovereign state
de facto state
http://en.wikipedia.org/wiki/Sovereign_state
nation
nation state
governmental organization