Entität is a term for the rewriting of a partial state or a subpopulation. The word is a direct transmission from the English, itself in the 90's the 20. Century in the policy in-patriated. The English expression “entity” meant about “belonging together unit” and becomes also in compositions like “legally entity” = “legal entity” related. The term might have been in-patriated particularly for reasons of a certain mental comfort with translating (Anglizismus), in addition, around itself not by defined terms as for instance partial state to specify province or autonomous area on people and state-legal status the region concerned.
A well-known example is the Dayton contract, that the individual population parts in Bosnia and Herzegowina, which call Republika Srpska and the federation Bosnia-Herzegovina “entities” and so that evades to the open legal questions.