Definition of slag in English:



  • 1Stony waste matter separated from metals during the smelting or refining of ore.

    • ‘The hardened matter was slag, a waste product from metal working, and contained evidence of iron, copper and lead manufacture.’
    • ‘By contrast, the lunar regolith ‘has a composition similar to mining slag.’’
    • ‘Vincent snorted, and turned the doorknob into molten slag once it had swung shut again.’
    • ‘We started making turns around the slag piles at the mine.’
    • ‘Some people had even died in slag slides, picking loose bits of coal in order to keep their homes heated.’
    • ‘The union has leveled 15 separate charges against Levy, a contractor at Mittal Steel USA, which performs slag processing and metal reclamation.’
    • ‘The concentrates are refined by smelting - they are melted, and the impurities are removed as a slag.’
    • ‘The waste product slag was also increasingly used in road and house building.’
    • ‘Ores, slag and ash exports during the first seven months amounted to $644 million, up 77 per cent over the same period last year.’
    • ‘Piles of black slag marked the entrances to small coal mines.’
    • ‘In highly developed countries, the major components of industrial waste are blast furnace and steel slag, and power station ash.’
    • ‘Under suitable slag conditions vanadium, in quite small quantities, ‘cleans’ the steel and renders it free from slag inclusions.’
    • ‘This artificial uranium mine is contained in the slag material from power station coal combustion and deposited in landfills.’
    • ‘Ground granulated blast furnace slag is used in 53 % of councils in NSW and 23 % in VIC.’
    • ‘"Oh, it used to be a slag heap, " John said.’
    • ‘The road is unusually constructed of compacted iron slag.’
    • ‘The blasts shot towards the small shielded orb and reduced the metal to molten slag.’
    • ‘Tell me about Lehigh's interest in supplemental materials, like slag cement.’
    • ‘In particular, tuyeres in the furnace became blocked with slag.’
    • ‘Blast furnaces are used to recycle slag, dross, and residues from other processes.’
    1. 1.1Similar material produced by a volcano; scoria.
      • ‘Two recycled cementitious materials come to mind immediately - fly ash and slag cement.’
      • ‘The difference in densities of the molten iron and molten slag allow each material to be removed separately from the furnace.’
      • ‘I watched, slightly shocked, as molten metal slag fell onto the glass, steaming.’
      • ‘Kerosene has been used to light pyres constructed of coal slag, old tyres and tar-soaked rail sleepers.’
      • ‘Thirdly, reduce the clinker content in cement, by intergrinding cementious material like slag, fly ash, or limestone.’
      • ‘Mineral fiber insulation, including fiber glass and rock wool, is produced from either molten glass, slag, or rock.’
      • ‘The increasing size of the slag pile poses an ongoing threat to the richest remaining prairie site.’
      • ‘It was a more rustic and northern version of Detroit with escarpments of slag and iron ore.’
      • ‘It is usually caused by the scouring action of sand, gravel, slag, earth, and other gritty material.’
      • ‘The blasts shot towards the small shielded orb and reduced the metal to molten slag.’
      • ‘The stats and history of this limestone slag heap are impressive in their own right.’
      • ‘There were areas of bare rock and slag, which were around old gold mines, according to the naturalist.’
  • 2British derogatory, informal A promiscuous woman.

    • ‘But as soon as a women starts to pick and choose who she sleeps with she gets called a slag.’
    • ‘The women are slags, either scrawny with straggly blonde hair, or grotesquely fat and bulging out of their tracksuit bottoms.’
    • ‘Boys continued to make the same distinction between prospective wives and slags.’
    • ‘She told him Trev had called her a dirty slag after their drink the other night and had refused to sleep with her.’
    • ‘Not so many slags frequent this public house anymore - each time we go in there the ratio of men to women is rising.’
    • ‘If you look beyond the dehumanising stereotypes to the hard facts, it emerges that females in jail are not conniving slags.’
    • ‘The place was full of big bellied old West Ham supporters, complete with navy tattoos with the fat slags from Viz in tow.’
    • ‘Alastair's so used to working in a serious environment, he couldn't believe fellas were coming at him with slags.’


  • Produce deposits of slag.


Mid 16th century: from Middle Low German slagge, perhaps from slagen strike with reference to fragments formed by hammering.