1. conforming to fact and therefore worthy of belief

- an authentic account by an eyewitness

Similar word(s): trustworthy, trusty, reliable

2. not counterfeit or copied

- an authentic signature

Similar word(s): echt, genuine, unquestionable, veritable

Sentences with authentic as an adjective:

- The experts confirmed it was an authentic signature.

- The report was completely authentic.

- an authentic writer; an authentic portrait; authentic information