ullage, n. [OF. eullage, ouillage, the filling up of a cask, fr. ouillier, oillier, euillier, to fill a wine cask; properly, to add oil to prevent evaporation, as to a flask that is nearly full, fr. OF. oile oil. See Oil.].
The amount which a vessel, as a cask, of liquor lacks of being full; wantage; deficiency. [1913 Webster]