authenticity

I had trouble today in class with the difference between original and authentic. The rolex and Tex-Mex examples helped a lot but i still didn't fully understand what made something authentic. And can something be a little authentic but not completely authentic? Original means by definition "that from which a copy, reproduction, or translation is made, or a work composed firsthand." Authentic means "conforming to an original so as to reproduce essential features." So does this mean any replica that conforms to the original is authentic. That would mean that even the Walmart copy of a rolex would be authentic. But the definition also says "made or done in the same way and the original" and "not false or imitation." The first quote makes it seem like a Walmart rolex could be a little authentic because it has the essential features of a rolex, but according to the second quote it cannot be an imitation. I feel like the third quote contradicts the first two because anything that is not an original is some kind of imitation or replica. It seems by this third quote that the only thing that can be authentic besides the original is something that comes with a name. Again using the rolex example, all rolexes are bases on an original design but they are still authentic rolexes. An object then, it seems, must come with a name or a special genuineness in order to be considered authentic. For example a designer bag is always authentic as long as it carries a brand name. A Picasso is always authentic as long as he painted it himself. So a replica can always be authentic as long as it isn't a knock off or imitation.  

(definitions taken from Merriam-Webster online)