nation: a group of people often sharing common elements of culture such as religion or language, or a history or political identity.

territory: the delimited area over which a state, an individual, or a group exercises control and which is recognized by other states, individuals, or groups.

states: independent political units with territorial boundaries that are internationally recognized by other states. - A political organization in control of territory.

nation-state: an ideal form consisting of a homogeneous group of people governed by their own state.

unitary state: a form of government in which power is concentrated in the central government.

federal state: a form of government in which power is allocated to units of local government within the country.

See also "nationalism"

language: a means of communicating ideas or feelings by means of a conventionalized system of signs, gestures, marks, or articulate vocal sounds.

language family: a collection of individual languages believed to be related to their prehistorical origin.

example: Indo-European languages in Europe. Which languages are not Indo-European? Where did their people's come from?

language branch: a collection of languages that possess a definite common origin but have split into individual languages.

example: the Romance languages were based on the common root of Latin spread as the Lingua Franca of the Roman Empire.

Dialects: regional variations in standard languages.

Nation or State?
Matt Rosenberg - The Mining Company Geography

Independent States of the World - U.S. State Department list

Ethnologue Database - Nations of the World Listed by Language and Country