slag off

present singular third person slags off · participle present slagging off · participle past slagged off · past slagged off

1. transitiveTo purify by melting and removing slag.

   There is a lot of copper oxide, but I can remove that by melting everything and slagging it off.

2. CommonwealthIrelandUKslangtransitiveTo talk insultingly to or about someone or something; usually one who is not present.

   I am forever slagging off some poor harmless dude or pitiful demented twitcher[.]

   1983, Bill Oddie, Gone Birding, London: Methuen, page 1

   2 more examples

   There’s pressure to be a brand. I’m even locked out of my social media because I just get drunk and slag people off.

   2023 February 24, Michael Segalov, quoting Will Young, “Will Young: ‘I’m locked out of my social media because I get drunk and slag people off’”, in The Guardian, →ISSN

   The Donald didn’t seem convinced and started slagging off the London mayor, Sadiq Khan. “He’s a friend of mine,” squeaked Starmer.

   2025 July 28, John Crace, “Sidekick Starmer can’t get a word in as The Donald dominates world’s most one-sided double act”, in The Guardian, →ISSN

   Synonyms: abuse, insult, slur, abuse, affront, burn, carry, cut down