What is "veraison"

n. A stage in the ripening process of grapes or olives. It is the relatively short period during which the firm, green berries begin to soften and change colour.

In viticulture (grape-growing), veraison is the onset of ripening. The term is originally French (véraison), but has been adopted into English use. The official definition of veraison is "change of color of the grape berries". Veraison represents the transition from berry growth to berry ripening, and many changes in berry development occur at veraison.