ullage

noun

1. (countable, uncountable)In a wine bottle, the empty space between the cork and the top of the wine.
2. (countable, uncountable)In a cask or barrel, the empty space, occupied by air, that is created by not completely filling the cask or barrel, or through spillage.

   “The dry ullage will be obtained in the same manner, the dry inches being used instead of the wet.”

3. (countable, uncountable)The topping up of such a barrel with fresh wine.
4. (countable, uncountable)In an industrial setting, the empty space in a tank, especially as for fuel.

   “Upon completion of loading, all cargo tanks shall again be inspected and ullages carefully measured and recorded, with temperatures, in the Cargo Record Book, Port Log and Supplementary Loading and Discharging Report.”

   “According to the Colombian Government's report regarding this accident, the bomb explosion itself did not compromise the structural integrity of the airplane; however, the explosion punctured the CWT and ignited the Jet A fuel/air vapor in the ullage, resulting in the destruction of the airplane.”

5. (countable, uncountable)Additional cargo of little or no value taken on to prevent movement or shifting of the purposive cargo.

   “[…]5 hhds. rum/ 5 bbls. flour/ 1 bbl. sugar/ 9 do. pork/ 1 do. suett/ 3 do. cocoa/ 6 do. peas/ 2 ullage bbls. vinegar[…]”

6. (countable, in-plural, obsolete, slang, uncountable)Leftover wine surreptitiously drunk by waiters as they clear away the glasses.

   “Mopps […] was draining his vast array of wine-glasses, lest the waiters carrying them off should find any "ullages" in them for surreptitious tippling on stair-cases.”

verb

1. To gauge the amount of empty space between the top of a cask and the level of liquid inside it.

   “The Duties on Spirits in England are charged on the number of proof gallons they contain, which is ascertained by first “gauging” or “ullaging” the liquor, and then “trying its strength” by Sike's hydrometer, in the way already described […]”