I find the term nation-state to misleading. Technically, the term state defines a condition of clear legal identity with the components noted of government and control. States are arbitrary constructs.
The term nation would refer more strongly to the perceived identity of the people, either by language, custom, ethnicity, etc. Nations are nebulous, ever changing things that are difficult to control or keep from evolving.
A nation state would therefore be a more rare condition (rare by today's standards anyway) of a state with a single national identity. Germany would likely be a worthwhile example of a nation-state. Until dunne comes along and reminds me that would only be true if it included Austria - and I would add probably some small sections of other surrounding countries. It is a rare thing indeed.