barbarian vs uncivilised

barbarian is a noun but uncivilised is not a noun.

Word	Noun	Adjective	Verb	Adverb
barbarian	Yes	Yes	No	No
uncivilised	No	Yes	No	No

As adjectives, barbarian and uncivilised are synonyms defined as:

Other synonyms of barbarian include barbaric, savage, uncivilized, wild.

barbarian (noun)	uncivilised (noun)
a member of an uncivilized people
a crude uncouth ill-bred person lacking culture or refinement

barbarian (adjective)	uncivilised (adjective)
without civilizing influences	without civilizing influences