slag

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The vitreous mass left as a residue by the smelting of metallic ore.
2. n. See scoria.
3. v. To change into or form slag.

Century Dictionary and Cyclopedia

1. n. The earthy matter separated, in a more or less completely fused and vitrified condition, during the reduction of a metal from its ore. Slags are the result of the combination with one another, and with the fluxes added, of the silicious and other mineral substances contained in the ore, and they vary greatly in character according to the nature of the ores and fluxes used. Blast-furnace slags are essentially silicates of lime and alumina, the alumina having usually been present in the ore, and the lime added (in the form of carbonate of lime) as a flux, or as a means of obtaining a slag sufficiently fluid to allow of the easy and complete separation from it of the reduced metal. The slag of iron-furnaces is frequently called cinder.
2. n. The scoria of a volcano.
3. To form a slag, or to cohere when heated so as to become a slag-like mass.
4. n. A hollow or depression of land.
5. n. In the puddling process for making wrought-iron, the slag which forms when, as a preliminary step not always taken, air is blown down upon the surface of a charge of melted cask iron in a specially constructed hearth. Silicon is the principal substance removed from the iron, and the slag consists mainly of ferrous silicate.
6. In metal: To convert into slag: as, an excess of limestone used as a flux may to a greater or less extent slag the lining of a furnace.
7. To cake together as the result of chemical action at a heat lower than that of fusion.

Wiktionary

1. n. Waste material from a coal mine.
2. n. Scum that forms on the surface of molten metal.
3. n. Impurities formed and separated out when a metal is smelted from ore; vitrified cinders (Wikipedia).
4. n. Hard aggregate remaining as a residue from blast furnaces, sometimes used as a surfacing material.
5. n. Scoria associated with a volcano.
6. n. UK, pejorative, dated A coward.
7. n. UK, pejorative A contemptible person, a scumbag.
8. n. UK, pejorative A prostitute.
9. n. UK, Australia, New Zealand, slang, pejorative A woman (sometimes a man) who has loose morals relating to sex; a slut.
10. v. transitive To produce slag.
11. v. transitive, with "off" To talk badly about; to malign or denigrate (someone).
12. v. intransitive, Australia, slang To spit.

GNU Webster's 1913

1. n. The dross, or recrement, of a metal; also, vitrified cinders.
2. n. The scoria of a volcano.
3. n. (Metal.) 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.
4. v. (Metal.) To form, or form into, a slag; to agglomerate when heated below the fusion point.

WordNet 3.0

1. v. convert into slag
2. n. the scum formed by oxidation at the surface of molten metals