Definition of slag in English:



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

    ‘the burning liquid iron was forming a scum of slag’
    • ‘In highly developed countries, the major components of industrial waste are blast furnace and steel slag, and power station ash.’
    • ‘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.’’
    • ‘The waste product slag was also increasingly used in road and house building.’
    • ‘This artificial uranium mine is contained in the slag material from power station coal combustion and deposited in landfills.’
    • ‘Tell me about Lehigh's interest in supplemental materials, like slag cement.’
    • ‘Blast furnaces are used to recycle slag, dross, and residues from other processes.’
    • ‘Ores, slag and ash exports during the first seven months amounted to $644 million, up 77 per cent over the same period last year.’
    • ‘Under suitable slag conditions vanadium, in quite small quantities, ‘cleans’ the steel and renders it free from slag inclusions.’
    • ‘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 concentrates are refined by smelting - they are melted, and the impurities are removed as a slag.’
    • ‘The road is unusually constructed of compacted iron slag.’
    • ‘The union has leveled 15 separate charges against Levy, a contractor at Mittal Steel USA, which performs slag processing and metal reclamation.’
    • ‘Vincent snorted, and turned the doorknob into molten slag once it had swung shut again.’
    • ‘The blasts shot towards the small shielded orb and reduced the metal to molten slag.’
    • ‘In particular, tuyeres in the furnace became blocked with slag.’
    • ‘We started making turns around the slag piles at the mine.’
    • ‘Piles of black slag marked the entrances to small coal mines.’
    • ‘Some people had even died in slag slides, picking loose bits of coal in order to keep their homes heated.’
    1. 1.1Stony material ejected by a volcano; scoria.
      [count noun] ‘flow after flow of lava, slags, powders, and ejecta cast upon the previous outpourings in grotesque patterns’
      • ‘It is usually caused by the scouring action of sand, gravel, slag, earth, and other gritty material.’
      • ‘It was a more rustic and northern version of Detroit with escarpments of slag and iron ore.’
      • ‘The blasts shot towards the small shielded orb and reduced the metal to molten slag.’
      • ‘The increasing size of the slag pile poses an ongoing threat to the richest remaining prairie site.’
      • ‘There were areas of bare rock and slag, which were around old gold mines, according to the naturalist.’
      • ‘Mineral fiber insulation, including fiber glass and rock wool, is produced from either molten glass, slag, or rock.’
      • ‘The stats and history of this limestone slag heap are impressive in their own right.’
      • ‘Two recycled cementitious materials come to mind immediately - fly ash and slag cement.’
      • ‘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.’
      • ‘The difference in densities of the molten iron and molten slag allow each material to be removed separately from the furnace.’
  • 2British informal, derogatory A promiscuous woman.

    • ‘She told him Trev had called her a dirty slag after their drink the other night and had refused to sleep with her.’
    • ‘The place was full of big bellied old West Ham supporters, complete with navy tattoos with the fat slags from Viz in tow.’
    • ‘The women are slags, either scrawny with straggly blonde hair, or grotesquely fat and bulging out of their tracksuit bottoms.’
    • ‘Alastair's so used to working in a serious environment, he couldn't believe fellas were coming at him with slags.’
    • ‘If you look beyond the dehumanising stereotypes to the hard facts, it emerges that females in jail are not conniving slags.’
    • ‘Boys continued to make the same distinction between prospective wives and slags.’
    • ‘But as soon as a women starts to pick and choose who she sleeps with she gets called a slag.’
    • ‘Not so many slags frequent this public house anymore - each time we go in there the ratio of men to women is rising.’
    1. 2.1A contemptible or insignificant person.
      • ‘I created it especially to deal with nosey slags like you!’


  • 1[no object] Produce deposits of slag.

    ‘the furnace burns at a minimum temperature to reduce slagging’
  • 2British informal [with object] Criticize (someone) in an abusive and insulting manner.

    ‘my girlfriend was always slagging him off’
    • ‘People can think I'm stupid, they can slag me off, but I have tried to put forward both sides.’
    • ‘I used to slag him that he was a redneck in a jackeen's body.’
    • ‘The thing about Ricky is - I mean, I'm not just trying to slag him off - he's a nightmare to work with.’
    • ‘When he does those anthologies he gets slagged by the critics but they're the books that sell and support everything else that he does.’
    • ‘They slagged us off when we first started and said we wouldn't be around for five minutes.’
    • ‘The thing about Rodney is you don't want to take him too seriously because he's slagged off everyone in the world.’
    • ‘Fair play to my team mates and everyone at the bar because no one slagged me.’
    • ‘Of course, if you don't care about that and just want to slag people off, that's a good way to do it.’
    • ‘Meanwhile, Hain himself can slag people off just because they don't conform to his narrow vision of what constitutes a Brit.’
    • ‘We all get on really well and I've never slagged anybody off.’
    • ‘As much as certain people like to slag him off, when Jones doesn't play I feel we really struggle for goals.’
    • ‘I mean this is the guy who slagged the woman off every chance he got.’
    • ‘Although I'm a very powerful man my work chums slag me constantly for my Dublin accent and terrible stutter.’
    • ‘People slag me off because I'm a larger-than-life character, and that's part of my thing from the past - I lived my life very excessively.’
    • ‘They even slagged us off for asking the guests to donate money to charity instead of giving us presents.’
    • ‘There's no need for anyone to slag us off because they don't know us as people.’
    • ‘It's kinda funny, people slagged us off for putting all the names on the press release and people still got it wrong.’
    • ‘It's definitely a chink in the armour for people being able to slag me.’
    • ‘I slagged him off in the pub and everyone went a deadly quiet.’
    • ‘I was utterly slagged off and called several names.’
    find fault with, censure, denounce, condemn, arraign, attack, lambaste, pillory, disapprove of, carp at, cavil at, rail against, inveigh against, cast aspersions on, pour scorn on, disparage, denigrate, deprecate, malign, vilify, besmirch, run down, give a bad press to
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Mid 16th century: from Middle Low German slagge, perhaps from slagen strike, with reference to fragments formed by hammering. The verb sense ‘criticize’ dates from the 1970s.