rock salmon vs Britain

rock salmon and Britain both are nouns.

Word	Noun	Adjective	Verb	Adverb
rock salmon	Yes	No	No	No
Britain	Yes	No	No	No

rock salmon (noun)	Britain (noun)
any of several coarse fishes (such as dogfish or wolffish) when used as food	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