From Middle English ulage, from Anglo-Norman ulliage, from *ullier (“to fill a partially empty cask”), from Old French oel (“bunghole", literally, "eye”), from Latin oculus (“eye”). See French ouillage.
- In a wine bottle, the empty space between the cork and the top of the wine.
- In a cask or barrel, the empty space, occupied by air, that is created by not completely filling the cask or barrel.
- The topping-up of such a barrel with fresh wine.
- In an industrial setting, the empty space in a tank, such as for fuel.
- To gauge the amount of empty space between the top of a cask and the level of liquid inside it.