Definition - What does Legs mean?
The legs of a wine, sometimes called "tears," are the drops of wine which run down the inside of a wine glass after swirling the wine. It is caused by the evaporation of alcohol. Legs may also help determine the quality of a wine based on their viscosity. They can indicate a high-alcohol wine or one with significant levels of residual sugar.
WineFrog explains Legs
The legs of a wine can be observed when one swirls a wine in a wine glass or decanter. They form when drops of wine run down the inner sides of the glass. Many claim that it can help identify a quality wine. Contrary to popular belief that slow-running and wide legs indicate a quality wine, legs of the same wine can change due to varying barometric pressures and a room's temperature. They are not always a consistent indicator of quality wine. One exception of noting a lesser-quality wine, however, would be one that has "legs" which wash down the inside of a glass as water would. In general, wines with thick and slow-running legs are high in alcohol and/or residual sugar.