au·then·tic
 /əˈθɛntık/  adj  
  1 : real or genuine : not copied or false
   We saw authentic examples of ancient Roman sculpture.
   The document is authentic.
   Experts have confirmed that the signature on the letter is authentic.
  2 : true and accurate
   The witness provided an authentic record/report/account of what actually took place.
  3 [more ~; most ~] : made to be or look just like an original
   The actors were dressed in authentic medieval costumes. [=costumes that looked just like real medieval clothes]
   She prepared a very authentic Mexican meal.
   The building is an authentic reproduction of a colonial farmhouse.
  au·then·ti·cal·ly /əˈθɛntıkli/  adv  
   authentically prepared Mexican food
  au·then·tic·i·ty /ˌɑːˌθɛnˈtısəti/  noun   [  noncount  ]
   We checked the authenticity of the signature.