Cymru vs Britain

Cymru and Britain both are nouns.

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

Cymru (noun)	Britain (noun)
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