A historical liquid measure for wine, which usually meant a wooden barrel or a wooden container with different volumes. The term is derived from "barrel binding" (see under cooper). In modern usage, this means a wine filled in a barrel or tank in an indeterminate quantity. In a broader sense, it can also indicate the quality of the wine; a wine bottled exclusively in a container (i.e. not in bottles) is usually of simple quality, which is referred to as cask wine or draught wine. However, the term is also generally used for wine containers of all kinds made of various materials (wood, ceramic, stainless steel).
For me, Lexicon from wein.plus is the most comprehensive and best source of information about wine currently available.
Egon Mark
Diplom-Sommelier, Weinakademiker und Weinberater, Volders (Österreich)