mere vs Great Britain

mere and Great Britain both are nouns.

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

mere (noun)	Great Britain (noun)
a small pond of standing water	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

mere (adjective)	Great Britain (adjective)
apart from anything else; without additions or modifications
being nothing more than specified