Etymology Borrowed from Middle Low German slagge, slaggen (“slag, dross”), from Old Saxon *slaggo, from Proto-West Germanic *slaggō, from Proto-Germanic *slaggô, from Proto-Germanic *slagōną (“to strike”) + *-gô (diminutive suffix). Compare Middle Low German slāgen (“to strike”), since originally the splinters struck off from the metal by hammering, from *slagōn, from Proto-West Germanic *slagōn. Compare also Old Saxon slegi, from Proto-West Germanic *slagi. See also Dutch slak, German Schlacke, Swedish slagg; also compare English slay.
After the big village, the scenery had returned to grass and woodland, but this had now given way to ugly mounds of discarded slag. Beyond the slag was a colliery with its machinery and smoking chimney, making the whole area look grim and austere.2011, Vivienne Dockerty, A Woman Undefeated, page 54:
2
Scum that forms on the surface of molten metal.
2006, Melisa W. Lai, Michele Burns Ewald, Chapter 95: Silver, Martin J. Wonsiewicz, Karen G. Edmonson, Peter J. Boyle (editors), Goldfrank′s Toxicologic Emergencies, 8th Edition, page 1358, 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.
He leans out over the track and skims slag off the top of the boiling steel, risking what is called “catching a flyer,” which occurs when hot metal explodes out of the mold, spraying everyone in the vicinity.2009, John Hoerr, Monongahela Dusk, page 255:
3
Impurities formed and separated out when a metal is smelted from ore; vitrified cinders.
Buried within the Mediterranean littoral are some seventy to ninety million tons of slag from ancient smelting, about a third of it concentrated in Iberia. This ceaseless industrial fueling caused the deforestation of an estimated fifty to seventy million acres of woodlands.2006, Edwin Black, chapter 2, in Internal Combustion:
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, Barbara S. Ottaway, Ben Roberts, “The Emergence of Metalworking”, in Andrew Jones, editor, Prehistoric Europe: Theory and Practice, page 207:
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Hard aggregate remaining as a residue from blast furnaces, sometimes used as a surfacing material.
During blast furnace operations, the plant operator pays careful attention to the slag chemistry (both composition and variability) as slag behavior is a major consideration in ensuring the quality of hot metal (molten iron).2006, Jan R. Prusinski, “44: Slag as a Cementitious Material”, in Joseph F. Lamond, James H. Pielert, editors, Significance of Tests and Properties of Concrete and Concrete-Making Materials, page 517:
All these properties are determined by slag composition and its temperature. In basic slags, foaming ability increases as SiO₂ concentration grows.2010, Yuri N. Toulouevski, Ilyaz Y. Zinurov, Innovation in Electric Arc Furnaces, Springer, page 16:
1984, Tristan Jones, Heart of Oak, 1997, paperback edition, page 260, We never talked about that, of course; we talked about how we could find a woman in the Dilly, and if the Yanks had taken them all, how we could always resort to the peroxided older slags who hung out around the side doors to Waterloo station and did knee tremblers for the Yanks.
Which grotesque auld hing-oot will the shrivelled post-menopausal slag want tae shaft? Stay tuned.1994 [1993], Irvine Welsh, Trainspotting, London: Minerva, →ISBN, page 252:
4 more examples
2002, Josephine Cox, The Woman Who Left, 2012, ebook, unnumbered page, ‘Slag! Wait till I tell Jacob what we′ve been doing – and I will, you mark my words! He′ll want nowt to do with you then, will he, eh? He′ll see you for what you really are. A cheap and nasty little bitch!’
‘[…]He was a lovely man but, when I told him I wanted to continue swinging, he freaked out and called me a slag.’2008, Ashley Lister, Swingers - Female Confidential, page 31:
‘[…]To the lady that came in to my coffee shop today and ripped on me and my fellow employees for being too slow: eat shit, you miserable slag!’2010, The Coast, Halifax, Canada:
Soph, yeah, you can't murk me / You're a slag, riddled with STDs2016 December 3, Millie B, “Soph Aspin Send”, performed by Millie B:
The writers took it for granted that England, with its working class composed of slags, purple-nosed losers, and animals fed on pinball, pornography and junk-food, was disintegrating into terminal class-struggle.1990, Hanif Kureishi, The Buddha of Suburbia, London; Boston: Faber and Faber, →ISBN, page 207:
The sycophantic slags all say / "I knew him first, and I knew him well"1987, “Paint a Vulgar Picture”, in Morrissey (lyrics), Johnny Marr (music), Strangeways, Here We Come, performed by The Smiths:
2 more examples
Kill him. Kill the royal slag.1996, Sarah Kane, “Phaedra's Love”, in Sarah Kane: Complete Plays, published 2001, Scene 8, page 100:
Can't believe it's been nearly 11 years since them slags smashed into the twin towers2012 September 13, Alexis Petridis, quoting Danny Dyer (tweet), “Danny Dyer: why them 9/11 slags are freaking his nut”, in The Guardian:
Etymology Borrowed from Middle Low German slagge, slaggen (“slag, dross”), from Old Saxon *slaggo, from Proto-West Germanic *slaggō, from Proto-Germanic *slaggô, from Proto-Germanic *slagōną (“to strike”) + *-gô (diminutive suffix). Compare Middle Low German slāgen (“to strike”), since originally the splinters struck off from the metal by hammering, from *slagōn, from Proto-West Germanic *slagōn. Compare also Old Saxon slegi, from Proto-West Germanic *slagi. See also Dutch slak, German Schlacke, Swedish slagg; also compare English slay.
1
To produce slag.
2
To become slag; to agglomerate when heated below the fusion point.
3
To reduce to slag.
4
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, Courtenay Young, Help Yourself Towards Mental Health, page 344:
Rather than wait for her to start slagging my mother, I would disappear for a couple of days and inevitably, because I was getting no love at home, I began to stray once again.2011, John Davies, Slings and Arrows, page 109:
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Ireland, Slang To make fun of; to take the piss (tease, ridicule or mock).