n. A kind of cloth suitable for making mantles or the like.—2. In the manufacture of alum from aluminous shales or alum ores, a layer of calcined shale spread over a partly or completely calcined heap of the same material, to moderate the heat, prevent loss of sulphur, and protect the mass from the detrimental effects of wind and rain during the calcination and cooling.n. In heraldry: The drapery which is often used as a background to a shield, crest, etc., originally perhaps the mantelet of the helmet or cointoise.n. A mantelet, lambrequin, or cointoise. Also mantle.