Great Britain vs whitefish

Great Britain and whitefish both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
whitefish	Yes	No	No	No

Great Britain (noun)	whitefish (noun)
an island comprising England and Scotland and Wales	silvery herring-like freshwater food fish of cold lakes of the Northern Hemisphere
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	flesh of salmon-like or trout-like cold-water fish of cold lakes of the Northern Hemisphere
	any market fish--edible saltwater fish or shellfish--except herring