Great Britain vs medium wave

Great Britain and medium wave both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
medium wave	Yes	No	No	No

Great Britain (noun)	medium wave (noun)
an island comprising England and Scotland and Wales	a radio wave with a wavelength between 100 and 1000 meters (a frequency between 300 kilohertz and 3000 kilohertz)
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