slag /ˈslæɡ/noun 8verb 6forms 3phrases 1 noun8 •Scum that forms on the surface of molten metal.In Asia Minor and on islands in the Aegean Sea, dumps of slag (scum formed by molten metal surface oxidation) demonstrate that silver was being separated from lead as early as 5000 BC. — 2006 •Impurities formed and separated out when a metal is smelted from ore; vitrified cinders.Consequently, mounds of large ‘cakes’ of slag are often found near the smelting sites of the Late Bronze Age, as for example at Ramsau in Austria (Doonan et al. 1996). — 2008 •Hard aggregate remaining as a residue from blast furnaces, sometimes used as a surfacing material.All these properties are determined by slag composition and its temperature. In basic slags, foaming ability increases as SiO₂ concentration grows. — 2010 •(slang, offensive) A prostitute or promiscuous woman; a slut.Which grotesque auld hing-oot will the shrivelled post-menopausal slag want tae shaft? Stay tuned. — 1994 •Waste material from a mine. •(UK, offensive) A contemptible person, a scumbag.The sycophantic slags all say / "I knew him first, and I knew him well" — 1987 •Scoria associated with a volcano. •(offensive, old-fashioned) A coward. verb6 •(UK, slang) To talk badly about; to malign or denigrate (someone).If you slag off the other person, then—to the extent that your child identifies with that person as their parent—you are slagging off a part of them. — 2010 •(Ireland, slang) To make fun of; to take the piss (tease, ridicule or mock). •To produce slag. •To become slag; to agglomerate when heated below the fusion point. •To reduce to slag. •(Australia, slang) To spit. formsslagged · slagging · slags Phrases with slag slag offTo talk insultingly to or about someone or something; usually one who is not present.