Great Britain vs Cymru

Great Britain and Cymru both are nouns.

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

Great Britain (noun)	Cymru (noun)
an island comprising England and Scotland and Wales	one of the four countries that make up the United Kingdom of Great Britain and Northern Ireland; during Roman times the region was known as Cambria
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