plain flour vs Great Britain

plain flour and Great Britain both are nouns.

Word	Noun	Adjective	Verb	Adverb
plain flour	Yes	No	No	No
Great Britain	Yes	No	No	No

plain flour (noun)	Great Britain (noun)
flour that does not contain a raising agent	an island comprising England and Scotland and Wales
	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