Pronunciation: (ô-then'tik),[key] —adj. 1. not false or copied; genuine; real: an authentic antique. 2. having the origin supported by unquestionable evidence; authenticated; verified: an authentic document of the Middle Ages; an authentic work of the old master. 3. entitled to acceptance or belief because of agreement with known facts or experience; reliable; trustworthy: an authentic report on poverty in Africa. 4. Law.executed with all due formalities: an authentic deed. 5. Music. a. (of a church mode) having a range extending from the final to the octave above. Cf. plagal. b. (of a cadence) consisting of a dominant harmony followed by a tonic.