United Kingdom of Great Britain and Northern Ireland vs guest night

United Kingdom of Great Britain and Northern Ireland and guest night both are nouns.

Word	Noun	Adjective	Verb	Adverb
United Kingdom of Great Britain and Northern Ireland	Yes	No	No	No
guest night	Yes	No	No	No

United Kingdom of Great Britain and Northern Ireland (noun)	guest night (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	an evening when members of a club or college can bring their friends as guests