Definition of slag:
- A product of smelting, containing, mostly as silicates, the substances not sought to be produced as matte or metal, and having a lower specific gravity than the latter; -- called also, esp. in iron smelting, cinder. The slag of iron blast furnaces is essentially silicate of calcium, magnesium, and aluminium; that of lead and copper smelting furnaces contains iron.
- Same as Basic slag, above.
- The dross, or recrement, of a metal; also, vitrified cinders.
- The scoria of a volcano.
- To form, or form into, a slag; to agglomerate when heated below the fusion point.
residue (part of speech: noun)