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ullage (UHL-ij) - n., the volume by which a container of liquid falls short of being full.
The air in a wine bottle or cask, a tank of fuel, and so on. In a barrel of wine, it's important to keep the ullage small as too much oxygen can sour the contents. In rocketry, it's important to start with enough ullage for the propellant to expand into as it heats up. In the tank of a car or truck, it's just the minor annoyance of being not quite topped off. In use since at least the 1400s, borrowed from Middle French or Anglo-Norman ulliage, from ouiller, to fill up a cask to the bung-hole, from oel or oeil, bunghole, literally eye, from Latin oculus eye. By which you can tell that to the French, and the Romans before them, the winemaker's sense was the important one.
---L.
The air in a wine bottle or cask, a tank of fuel, and so on. In a barrel of wine, it's important to keep the ullage small as too much oxygen can sour the contents. In rocketry, it's important to start with enough ullage for the propellant to expand into as it heats up. In the tank of a car or truck, it's just the minor annoyance of being not quite topped off. In use since at least the 1400s, borrowed from Middle French or Anglo-Norman ulliage, from ouiller, to fill up a cask to the bung-hole, from oel or oeil, bunghole, literally eye, from Latin oculus eye. By which you can tell that to the French, and the Romans before them, the winemaker's sense was the important one.
---L.
