1. Glycerol - a sweet syrupy hygroscopic trihydroxy alcohol HOCH2CHOHCH2OH that occurs combined as glycerides and is formed by alcoholic fermentation of sugars, that is usu. obtained as a by-product in the manyfacture of soap or fatty acids by the saponification of fats or as a synthetic product from propylene or allyl alcohol, and that is used chiefly as a solvent and plasticizer, as a moistening agent, emollient, and lubricant, as an emulsifying agent, and as a starting material in the manufacture of many derivatives; 1,2,3-propane-triol - called also glycerin.
ref: Webster's International Unabridged Dictionary