Glycerin (glycerol, glycerine): the clear, sweet, syrupy liquid freed from fats and oils when they are made into soap or candle stock. Mixes with water in all proportions and draws moisture from the air. Used in soaps and cosmetics, resins (glyptal), medicines, inks and as an antifreeze. Grades run from crude soap-works glycerin to refined 99 % and pharmacopoeia (USP) grade, from animal or vegetable fats.