United Kingdom of Great Britain and Northern Ireland vs Sir

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

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

United Kingdom of Great Britain and Northern Ireland (noun)	Sir (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 title used before the name of knight or baronet