In the history of Rome, the Latin term civitas (plural civitates), according to Cicero in the time of the late Roman Republic, was the social body of the cives, or citizens, united by law (concilium coetusque hominum jure sociati). It is the law that binds them together, giving them responsibilities (munera) on the one hand and rights of citizenship on the other. The agreement (concilium) has a life of its own, creating a res publica or "public entity" (synonymous with civitas), into which individuals are born or accepted, and from which they die or are ejected. The civitas is not just the collective body of all the citizens, it is the contract binding them all together, because of which each is a civis. - Source: Wikipedia
