
1) Amount needed to fill a cask 2) Empty portion of a bottle 3) Grain lost through spilling 4) Indefinite quantity 5) Liquid amount lost in storage 6) Unfilled part of a wine cask 7) Wine left after leakage 
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https://www.crosswordclues.com/clue/ullage

1) Contents 
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https://www.crosswordclues.com/clue/ullage

 Ullage or headspace is the unfilled space in a container, particularly with a liquid. ==Etymology== The word comes ultimately from the Latin oculus, `eye”, which was used in a figurative sense by the Romans for the bung hole of a barrel. This was taken into French in the medieval period as oeil, from which a verb ouiller was created, to fill a.....
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http://en.wikipedia.org/wiki/Ullage
 [wine]
[wine]  Ullage (from the French ouillage) is a winemaking term that has several meanings but most commonly refers to the headspace of air between wine and the top of the container that it is in. It can also refer to the process of evaporation that creates the headspace itself or it can be used as a past tense verb to describe a wine barrel o...
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http://en.wikipedia.org/wiki/Ullage_(wine)

quantity by which vessel is under full capacity
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http://phrontistery.info/u.html

• (n.) The amount which a vessel, as a cask, of liquor lacks of being full; wantage; deficiency.
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http://thinkexist.com/dictionary/meaning/ullage/

The amount by which a container, such as a tank, falls short of being full.
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http://www.braeunig.us/space/glossary.htm

The extra volume of gas above the liquid propellant held in sealed tanks. This space allows for thermal expansion of the propellant or the buildup of gases released by the propellant.
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http://www.daviddarling.info/encyclopedia/U/ullage.html

The empty space above the liquid in a wine bottle (or wine barrel or tank) usually after long storage. Ullage is used as an indicator of how well a cork seals its bottle. It is highly unusual for a wine bottle to retain its fill point without ullage after long storage since all corks tend to allow seepage to greater or lesser extent. In a very old ...
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http://www.edenwines.co.uk/Glossary_u.html

If you ever buy old fine wines, you'll be interested in the ullage level: it refers to the loss of wine from the bottle with time and involves the gap between the cork and the surface of the wine. It can vary widely, even between bottles from the same case, and terms like 'low neck' and 'high shoulder' are used to describe it. These descriptors wil...
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http://www.encyclo.co.uk/local/20433

Also known as headspace, the unfilled space in a wine bottle, barrel, or tank.
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http://www.encyclo.co.uk/local/20673

French term for a not fully filled wine bottle, due to leakage through the cork.
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http://www.encyclo.co.uk/local/21216

The empty space above the liquid in a wine bottle, barrel or tank. Too much ullage can lead to unwanted aerobic bacteria growing on the surface of the wine. Corrected by topping.
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http://www.nebraskawines.com/wine-glossary/

 the empty space left in bottles and barrels as a wine evaporates. When  in barrels, one must keep ullage at a minimum so the wine does not  oxidize.
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http://www.vinology.com/dictionary/

A term that refers to calculating the headspace of a cask, keg or barrel.
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https://byo.com/resources/glossary

Also known as headspace, the unfilled space in a wine bottle, barrel, or tank.
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https://en.wikipedia.org/wiki/Glossary_of_wine_terms

 See under shrinkage. Loss Term for the loss of liquid in a wine container caused by evaporation, which occurs mainly in wooden containers but also in bottles sealed with natural corks. Wooden barrels are not absolutely leak-proof compared to tanks made of stainless steel, glass or ceramics, but there is a certain exchange of substances (liquid...
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https://glossary.wein.plus/ullage

The amount of empty space in a cask. The ullage of a cask will naturally increase over time due to the natural evaporation of spirit through this cask (angel’s share).
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https://www.bruichladdich.com/bruichladdich-whisky-news/making-whisky/gloss
 noun
 noun the amount that a container (as a wine bottle or tank) lacks of being full
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https://www.encyclo.co.uk/local/20974

The empty space above the liquid in a wine bottle (or wine barrel or tank) usually after long storage. Ullage comes from the French word ouillage. Older wine bottles typically have a little more space, or ullage, than younger wines because more of the wine has seeped out and evaporated away with time. Ullage is used as an indicator of how well a co...
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https://www.encyclo.co.uk/local/22305

The air space between the surface of the wine and the bottom of the bung, cork or other closure. In a cask or barrel, it is the volume of wine missing, which if present would result in a full container of wine. 
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https://www.encyclo.co.uk/local/22309

Any airspace above a wine when in tank or barrel. Ullage is avoided by topping up.
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https://www.encyclo.co.uk/local/22313

The empty space in a cask
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https://www.encyclo.co.uk/local/22617

See headspace.
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https://www.encyclo.co.uk/local/22622

the amount by which the contents fall short of filling a container, as a cask or bottle. · the quantity of wine, liquor, or the like, remaining in a container that has lost part of its contents by evaporation, leakage, or use. · the volume of a loaded tank of liquid propellant in excess of the volume of the propellant; the space provid...
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https://www.infoplease.com/dictionary/ullage
  No exact match found.