slag off

Definition

Slang

  • verb to denigrate, criticise bitterly or insult. This working-class term probably derives from the dialect ‘slag’, meaning to smear, or from the standard English noun ‘slag’, meaning refuse or waste material. In the form ‘slag’ the modern expression occurs in American speech. US authorities cite the German verb schlagen (to beat or lash), but this is an unlikely source for the British usage.
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