Definitions for ullageˈʌl ɪdʒ
Random House Webster's College Dictionary
the amount by which the contents fall short of filling a container, as a cask or bottle.
Origin of ullage:
1400–50; late ME < AF ulliage; OF ouillage,(h)eullage wine needed to fill a cask
the amount that a container (as a wine bottle or tank) lacks of being full
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
In an industrial setting, the empty space in a tank, such as for fuel
the amount which a vessel, as a cask, of liquor lacks of being full; wantage; deficiency