Metal DROSS is a waste product created during the smelting of metal ores. It is composed of impurities that are removed from the ore during the smelting process. The term 'DROSS' is derived from the Old English word 'drōsian, ' which means 'to be dry or withered.' The crossword solution for metal DROSS is SLAG, which is a by-product of the smelting process. SLAG is a glassy material that is formed when molten metal is exposed to air and cools quickly. It is usually gray or black in color and can contain metals, minerals, and other materials.