Waste material left over from metal smelting, or as a verb, to criticize someone harshly or insult them.
From Middle Low German 'slag' meaning waste from smelting, originally referring to the byproduct of metal refinement. The insulting meaning evolved in British slang in the 20th century, transferring the idea of unwanted waste to demeaning comments about people.
The word 'slag' started as a literal industrial term but took on a completely new insult meaning—it's a perfect example of how language recycles old words to express new attitudes, especially in working-class communities that worked around foundries and metal works.
In British English, 'slag' became a gendered slur for women (especially sex workers) by the mid-20th century, conflating waste material with dehumanization. The term perpetuates erasure of women's dignity and agency.
Use only in metallurgical/industrial contexts (waste byproduct). In social contexts, replace entirely; avoid the slur form.
["waste material","byproduct","dross"]
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