In wine, viscosity is expressed as body and weight.

Think about syrup or honey in your mouth: they feel thicker and move slower than water.

Or think about milk: skimmed moves more easily than whole or cream.

The main wine viscosity factor is alcohol: wines with 13,5% ABV and up tend to be full bodied.

Other viscosity factors are: residual sugar, glycerol, terroir, grape variety, vintage and temperature.

Sweet wines are more viscous than dry wines (more sugar).

High alcohol wines are more viscous than low alcohol wines.

Full body wines feel thick (heavy), light body wines feel thin.

Evaporation increases the viscosity: the more legs or the longer it takes to form, the more the viscosity.

In wine evaluation for viscosity, positive words are: fat, oily, meaty, supple, melting, thick.

Wine defect: lind (from Lindton, slimy), viscous.

Wine legs (aka tears, cathedral windows) are droplets formed inside the glass after swirling.

The scientific name is Marangoni effect.

This effect is due to alcohol evaporation and is completely eliminated if the glass is covered (preventing evaporation).

Because of this, it is incorrect to relate wine legs with wine quality.

The information that wine legs give us is the alcohol and sugar content (viscosity).

The higher the alcohol, the easier it is to form legs.

The higher the sugar, the slower the tears will flow down.