Unfilled part of a wine cask

• Amount lacking to make a full cask
• Amount needed to make a full cask
• Liquid lost from a container
• To capacity, lid off, time for the remaining liquid
• Liquid amount lost in storage
• Amount of liquid lost in shipping

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Ullage \Ul"lage\ (?; 48), n. [OF. eullage, ovillage, the filling up of a cask, fr. ouillier, oillier, euillier, to fill a wine cask; properly, to add oil to prevent evaporation, as to a flask that is nearly full, fr. OF. oile oil. See Oil .] (Com.) The ...

Wikipedia Word definitions in Wikipedia
Ullage (from the French ouillage ) is a winemaking term that has several meanings but most commonly refers to the headspace of air between wine and the top of the container holding the wine. It can also refer to the process of evaporation that creates the ...