Result of liquid loss in a cask

• Amount lacking to make a full cask
• The amount that a container (as a wine bottle or tank) lacks of being full
• Amount by which a cask falls short of being full
• Unfilled part of a wine container
• To capacity, lid off, time for the remaining liquid
• Liquid amount lost in storage
• Liquid lost from a container

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"amount by which a cask or bottle falls short of being full," late 15c., from Anglo-French ulliage (early 14c.), Anglo-Latin oliagium (late 13c.), Old French ouillage , from ouiller "to fill up (a barrel) to the bung," literally "to fill to the eye," from ...

Wikipedia Word definitions in Wikipedia
Ullage or headspace is the unfilled space in a container, particularly with a liquid.

WordNet Word definitions in WordNet
n. the amount that a container (as a wine bottle or tank) lacks of being full