authentic

Etymology

From Middle English authentik, from Old French autentique, from Latin authenticus, from Ancient Greek αὐθεντικός (authentikós, “principal, genuine”), from Ancient Greek αὐθέντης (authéntēs, “lord, master”).

adj

1. Of the same origin as claimed; genuine.
   The experts confirmed it was an authentic signature.
2. Conforming to reality and therefore worthy of trust, reliance, or belief.
   an authentic writer; an authentic portrait; authentic information
   The report was completely authentic.
3. (music, of a Gregorian mode) Having the final as the lowest note of the mode.
4. (obsolete) Authoritative.