Short definition
A specific batch or blend of wine, often used to indicate a producer's special selection or premium bottling.
In Champagne, "cuvée" originally meant the first and best pressing of the grapes. Now it is used loosely — "Cuvée Prestige" usually signals a top bottling, but "cuvée" alone might just mean "this particular batch." Some producers use it for their flagship wine, others for everything they make. Without other context, it tells you more about marketing than quality.