United Kingdom vs mere

United Kingdom and mere both are nouns.

Word	Noun	Adjective	Verb	Adverb
United Kingdom	Yes	No	No	No
mere	Yes	Yes	No	No

United Kingdom (noun)	mere (noun)
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	a small pond of standing water

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