Baudrillard's basic definition of hyperreality is the simulation of something that never really existed. Eco's definition is the "Authentic Fake." So it is a sign, a symbol, a representation, that only stands for itself. They seem to be saying that by it's very existence, the hyperreal eradicates the real. That if a simulation can be that convincing, with no origin in reality, then how do you distinguish the two? And if you can't distinguish them, then how can you define reality at all? It's quite a circular logic really, quite dependant on itself for it's own existence.