Ullage

Origin

From Middle English ulage, from Anglo-Norman ullage, from *ullier ("to fill a partially empty cask"), from Old French oel ("bunghole", literally, "eye"), from Latin oculus ("eye").

Full definition of ullage

Noun

1. In a wine bottle, the empty space between the cork and the top of the wine.
2. In a cask or barrel, the empty space, occupied by air, that is created by not completely filling the cask or barrel
3. The topping-up of such a barrel with fresh wine
4. In an industrial setting, the empty space in a tank, such as for fuel