foreign country vs body politic

foreign country and body politic both are nouns.

Word	Noun	Adjective	Verb	Adverb
foreign country	Yes	No	No	No
body politic	Yes	No	No	No

As nouns, body politic is a hypernym of foreign country; that is, body politic is a word with a broader meaning than foreign country:

foreign country: any state of which one is not a citizen
body politic: a politically organized body of people under a single government

Other hypernyms of foreign country include commonwealth, country, land, nation, res publica, state.

foreign country (noun)	body politic (noun)
any state of which one is not a citizen	a politically organized body of people under a single government