Britain vs copper's nark

Britain and copper's nark both are nouns.

Word	Noun	Adjective	Verb	Adverb
Britain	Yes	No	No	No
copper's nark	Yes	No	No	No

Britain (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