Definition - What does Millesime mean?
Millésime is the French word for “vintage” and notes the year in which the wine was produced and bottled. Winemakers prefer to note the year by the term millésime as opposed to année (which is the actual French translation for "year"). "Vintage" refers to the date in which grapes are harvested, undergo the vinification process to turn them into wine, and are bottled or stored for aditional aging.
The Millésime can note a vintage wine which is important in the French winemaking regions, especially the region of Champagne.
WineFrog explains Millesime
The vintage, or millésime, is important to include on a wine bottle's label because it can tell the purchaser if the wine should be aged or notes the quality of the wine. This is very true in European wines where the harvest can vary from one year to the next. The millésime can let the buyer know about the wine before even opening the bottle, depending on the year and region it was made in. It is also important to specify the millésime because it can describe the characteristics of the growing season for that year, which can indicate a certain quality and taste.
The word millésime was started to indicate the year on the Gregorian calendar that the wine was made in, according to the Conseil Internationale de la Langue Françias.