Cuvée is a wine term derived from the French word 'cuve', meaning vat or tank, though the term cuvée is used with many different meanings. On a wine label - it is used to denote a wine of a specific blend or batch. Since the use of the term cuvée for this purpose is unregulated, and most wines will have been in a tank at some stage in their production.
Please be aware that the presence of the word cuvée on a wine-label of an unknown producer, is no absolute guarantee of its superior quality. However, in the range of wines from a renowned producer who markets both regular blends and blends called 'cuvée', the cuvée-labeled wines will usually be a special blend or selected barrels of higher quality, when compared with that producer's regular wines.

 

Particularly terms like 'cuvée speciale', or 'tete de cuvée' (the latter especially in Sauternes AOP) should indicate a wine of very high quality and ageing potential.
Some wine producers differentiate higher-quality over ordinary cuvées as: 'reserve wines', while a cuvée lower in quality than the parent or primary wine is referred to as a 'second wine'. A cuvée wine-label may also be numbered, indicating that the winemaker has assigned a unique numbered series to that particular blend and volume.
In some wine regions, the term cuvée is used to specifically indicate a blend, i.e. a wine produced from a mixture of several grape varietals, rather than a single varietal wine. This is especially true in wine regions outside of France.
In Champagne and sometimes in other regions producing sparkling wines by; 'Methode Traditionnelle', the cuvée also refers to the best grape juice from the gentle pressing of the grapes (called the first pressing). In Champagne, the cuvée is the first 2050 litres of grape juice from 4000kg of grapes ('premier taille' - first tail), while the following 500 litres are known as the 'deuxieme taille' (second tail), and the juice due to the extra skin contact will make wines with a more coarse character and mouth-feel.
Several quality focused Champagne Houses (e.g. Charles Heidsieck, Piper Heidsieck, Pol Roger & Salon Champagne to name just a few) - pride themselves on only using the cuvée (first pressings) in their special cuvée sparkling wines.