Going to attempt brevity it never effin works. These are not dictionary or Encyclopedic defintions, just something from Inter. Relat. literature.
1. Nation=>A group of people that identify either ethnically, religiously;, or in some way that creates a strong culture(not sub-culture) and; self-identification with the culture.(think Nationality)Example: Nation of Islam
2. State=>A piece of land with borders, ruled over by a government. example: The United States(nationality Americans), Russia(nationality Slavic)
3. Nation-state=>A nation that has founded a state for themselves(often called homelands or such). A state that has adopted a national identity associated with a nationality.examples of not Nation-States: Americans: Nicaraguans, Mexicans, Canadians, etc. etc. Examples of Nation-States: Israel(Jewish), France(Norman), etc.
Assertion: The ideas we have been conditioned with as a Nation-State is all States are nation-states. This is incorrect and most likely arrived at, because old states such as France and Britain are Nation-States because they basically created a national identity over time. People are taught western society came to fruition with “Nation-States”.
Obviously the codified versions of these 3 defintions are approximately correct(at best) and open to interpretation. One can convey ideas much easier speaking and reading body language/receiving stimuli from the receiver. Peace