gun room vs United Kingdom of Great Britain and Northern Ireland

gun room and United Kingdom of Great Britain and Northern Ireland both are nouns.

Word	Noun	Adjective	Verb	Adverb
gun room	Yes	No	No	No
United Kingdom of Great Britain and Northern Ireland	Yes	No	No	No

gun room (noun)	United Kingdom of Great Britain and Northern Ireland (noun)
military quarters of midshipmen and junior officers on a British warship	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