Britannic vs Britain

Britannic is not a noun while Britain is a noun.

Word	Noun	Adjective	Verb	Adverb
Britannic	No	Yes	No	No
Britain	Yes	No	No	No

Britannic (noun)	Britain (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

Britannic (adjective)	Britain (adjective)
of Britain