Sentence:  The difference is important , for although the older law of nations did cover <WSD>relationships</WSD> among sovereigns , this was by no means its exclusive domain . 
Meaning of the word marked with <WSD> tags:  a relation between people; (`relationship' is often used where `relation' would serve, as in `the relationship between inflation and unemployment', but the preferred usage of `relationship' is for human relations or states of relatedness)