all-mains vs UK

all-mains is not a noun while UK is a noun.

Word	Noun	Adjective	Verb	Adverb
all-mains	No	Yes	No	No
UK	Yes	No	No	No

all-mains (noun)	UK (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

all-mains (adjective)	UK (adjective)
used of a radio receiver that is adaptable to all voltages