slags off

Verb

slag off (third-person singular simple present slags off, present participle slagging off, simple past and past participle slagged off)

1. (transitive) To 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. (Commonwealth, Ireland, UK, slang, transitive) To 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

   Synonyms:

   abuse, insult, slur, affront, burn, carry, cut down, disrespect, dis, diss