Great Britain vs half-term

Great Britain and half-term both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
half-term	Yes	No	No	No

Great Britain (noun)	half-term (noun)
an island comprising England and Scotland and Wales	a short vacation about halfway through a school term
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