authentic vs unquestionable

authentic and unquestionable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
authentic	No	Yes	No	No
unquestionable	No	Yes	No	No

As adjectives, authentic and unquestionable are synonyms defined as:

Other synonyms of authentic include bona fide, veritable.

authentic (adjective)	unquestionable (adjective)
not counterfeit or copied	incapable of being questioned
conforming to fact and therefore worthy of belief	not counterfeit or copied
	not open to question