supergrass vs United Kingdom of Great Britain and Northern Ireland

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

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

supergrass (noun)	United Kingdom of Great Britain and Northern Ireland (noun)
a police informer who implicates many people	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