A replicator was a device that could produce objects out of other molecules. It was most commonly associated with foods and beverages but industrial replicators were also used to mass-produce items or to produce larger items than what normal replicators would produce.
Certain people claimed that they could tell the difference between real and replicated food. For instance, Homer Simpson was able to tell real Duff beer from replicated beer. (RIS Bouteina: "Jockship")