Great Britain vs arterial road

Great Britain and arterial road both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
arterial road	Yes	No	No	No

Great Britain (noun)	arterial road (noun)
an island comprising England and Scotland and Wales	a major or main route
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