United Kingdom of Great Britain and Northern Ireland vs ploughman's lunch

United Kingdom of Great Britain and Northern Ireland and ploughman's lunch both are nouns.

Word	Noun	Adjective	Verb	Adverb
United Kingdom of Great Britain and Northern Ireland	Yes	No	No	No
ploughman's lunch	Yes	No	No	No

United Kingdom of Great Britain and Northern Ireland (noun)	ploughman's lunch (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 meal consisting of a sandwich of bread and cheese and a salad