Ullage

The remainder in a cask or package which has leaked or been partially used.

- Admiral William Smyth's Sailor's Word Book, 1867

Ullage of a cask is what such a vessel wants of being full.

- Edward Phillips' New World of English Words, 1706

The quantity of liquor contained in a cask partially filled, and the cpacity of the portion which is empty, are termed respectively the wet and dry ullage.

- Encylopedia Britannica, 1883

To Calculate the amount of ullage in a cask. To fill up again an ullaged cask.

- Sir James Murray's New English Dictionary, 1926