Great Britain vs inquiry agent

Great Britain and inquiry agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
inquiry agent	Yes	No	No	No

Great Britain (noun)	inquiry agent (noun)
an island comprising England and Scotland and Wales	a private detective
a monarchy in northwestern Europe occupying most of the British Isles; divided into England and Scotland and Wales and Northern Ireland; `Great Britain' is often used loosely to refer to the United Kingdom