U.K. vs copper's nark

U.K. and copper's nark both are nouns.

Word	Noun	Adjective	Verb	Adverb
U.K.	Yes	No	No	No
copper's nark	Yes	No	No	No

U.K. (noun)	copper's nark (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 informer or spy working for the police