Definition - What does Dry mean?
Dry is a wine tasting term that refers to the sensation, or lack there of, of wetness after drinking a wine. A dry wine is one that leaves the mouth feeling devoid of moisture. This is usually due to a lack of sugar or sweetness in a wine, but it can also be caused by high tannin or acidity levels. In fact, a wine is considered a “dry wine” when all of the grape sugar has been converted to alcohol during fermentation.
WineFrog explains Dry
Dry is a very subjective wine term, as everyone perceives sweetness differently. Some people prefer a dry wine over a sweet one, using the term to refer to a wine that is low in sugar. Others find that a wine's dryness is a negative aspect, because it lacks the necessary fruit to support the acidity and/or tannins. In this case, they’re referring to the fact that the wine’s fruit has faded, and its sugar has dissipated.
Levels of dryness are used for white and sparkling wines, as these styles tend to cater to a “drier” crowd. On French labels, the word “Sec” is used to indicate a dry wine. On Champagnes, the words “Brut”, "Dry" and "Extra Dry" are used to indicate the levels of dry Champagnes.
Dryness in a wine is caused by a combination of factors.
For Red Wines - Tannins are the components that cause red wines to be dry - these astringent components leave your mouth literally feeling dry and puckering. The more unripe tannins that are present in a wine, the drier it is. Another factor is the sugar level - the sweeter a wine, the less dry it seems.
White Wines - Dryness in white wines is caused by sugar levels. The sugar level (or sweetness) of the wine combined with the presence, or lack there of, of acidity contributes to a wine's final dryness. High acidity in a white wine can also leave your mouth feeling dry, like you’ve just sucked on a lemon.
Too much dryness in a wine could be indicative of a fading wine that is losing its fruit. For example, a wine that has spent too long in the barrel or bottle may be “dried out”.