United Kingdom vs slip carriage

United Kingdom and slip carriage both are nouns.

Word	Noun	Adjective	Verb	Adverb
United Kingdom	Yes	No	No	No
slip carriage	Yes	No	No	No

United Kingdom (noun)	slip carriage (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	a railway car at the end of the train; it can be detached without stopping the train