Definition - What does Glycerin mean?
By general definition, glycerin is the product of the fermentation of glucose, a syrupy liquid which can also be obtained from fat and animal oils. It has many uses as a sweetener when produced as food-grade glycerin, as a solvent, an antifreeze and in the making of soaps and explosives.
WineFrog explains Glycerin
In wine, glycerin or glycerol is an alcohol which is present from the fermentation of glucose.
Glycerin (glycerol) affects both the wine's flavor and texture. On the palate, glycerin adds a fuller note to wine and a soft mouth-feel. When introduced during the winemaking process, where it is most apparent, the texture of the wine can feel like a sugary drink, much like apple juice. It is also known as the alcohol responsible for the clinging action wine undergoes in the wine glass also known as the "legs", which run down the sides of the glass after sipping or swirling.