French term meaning "on the lees
After fermentation is complete, the expired yeast cells that converted the juice's sugar into alcohol will sink to the bottom of the tank or barrel. This sediment is known as the lees.
." As the wine rest on the spent yeast cells that are a by-product of fermentation, the yeast cells begin to decompose, potentially imparting a yeasty aroma, cramy texture, and increased complexity to the wine.