A term commonly used in the German-speaking world (Germany, Austria, Switzerland) to describe a certain amount of residual sugar in wine, which may optionally be indicated on the label. This is up to 4 g/l or up to 9 g/l if the total acidity is at most 2 g lower than the residual sugar. This means, for example, that if the residual sugar is 9 g/l, the total acidity must be at least 7 g/l. This acidity regulation has a practical meaning, as the sweetness is perceived less at higher acidity levels. With dry sparkling wine, where the sparkling carbonic acid gives a clearly different taste sensation, the residual sugar may even be between 17 and 32 g/l (this means already sweet with still wine).
Many experts consider a lowest level of up to 4 g/l to be legally sensible, because the range of up to 9 g/l is much too wide. Austria used the extra dry stage until its accession to the EU, but could not assert itself with regard to an EU-wide regulation. There are also the designations which are not relevant to wine law: Franconian dry, classic dry and Austrian dry with a maximum of 4 g/l as well as international dry (harmonious dry). The achievable lower limit for residual sugar is about 0.1 g/l. So there is no wine that contains no sugar at all. See regarding all flavours of still wine from dry to sweet under sugar content and regarding sparkling wine under sparkling wine.
A frequently asked question is what is the origin of the term "dry", which may seem strange for a liquid (when roasting food, this means the absence of fat and cooking oil). In the case of wine, however, it is not a question of the physical property of the absence of liquid, but of how much residual sugar is present. During fermentation, sugar is converted into alcohol and carbon dioxide (although this is never completely possible), so the rough rule of thumb is: the less sugar, the more alcohol. Alcohol is chemically hydrophilic (water-loving), which means that it is very soluble in water, thus binding water and even removing it from its environment. Something that lacks water is called dry. The alcohol in wine therefore leaves a rather dry feeling in the mouth, as it draws water from the mucous membrane. The lower the residual sugar content, the stronger this effect can be felt.
In the "German Dictionary of Jacob and Wilhelm Grimm", which was written from 1836 onwards and only finished long after the death of the two famous fairy tale authors in 1961, the following can be read under "dry" in relation to wine: In glossaries of the 14th and 15th century, "dry" or "trucking" is the frequent term for a wine that has been turned over and is mouldy and has a high content of acetic acid. In particular, acidic, tart, astringent liquids are considered dry and the term is also used to describe a fully fermented wine in which the sugar has been converted into alcohol, which has a tart, acidic taste. See also under flavour.