Wine viscosity refers to its liquid consistency. Wine viscosity will may make it appear thin and watery, or may make it appear thick and syrupy.
Viscosity is affected by the levels of glycerols (sugars) and alcohol found in the wine. Generally speaking, the higher a wine’s levels of glycerols and alcohol, the higher the wine’s viscosity will be.
Wines with high viscosity tend to cling to the side of a wine glass longer, and may leave “tears” or “legs” as bits of the wine begin to drip back down into the glass.