slag
1 Americannoun
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Also called cinder. the more or less completely fused and vitrified matter separated during the reduction of a metal from its ore.
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the scoria from a volcano.
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waste left over after the re-sorting of coal.
verb (used with object)
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to convert into slag.
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Metallurgy. to remove slag from (a steel bath).
verb (used without object)
noun
noun
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Also called: cinder. the fused material formed during the smelting or refining of metals by combining the flux with gangue, impurities in the metal, etc. It usually consists of a mixture of silicates with calcium, phosphorus, sulphur, etc See also basic slag
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a mass of rough fragments of pyroclastic rock and cinders derived from a volcanic eruption; scoria
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a mixture of shale, clay, coal dust, and other mineral waste produced during coal mining
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slang a coarse or dissipated girl or woman
verb
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slang (tr) (usually foll by off) to abuse (someone) verbally
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slang (intr) to spit
Usage
What else does slag mean? Content warning: the following content includes references to strong and sexist language. In slang, slag is an insulting British English term for a contemptible person. When used of women, it can be equivalent to slut. As a verb, to slag (off somebody) is "to attack (them) verbally," i.e., to talk smack about them.
Other Word Forms
Etymology
Origin of slag1
1545–55; < Middle Low German slagge; cognate with German Schlacke dross, slag; see slack 2
Origin of slag2
First recorded in 1780–90; originally an argot word for a worthless person or a thug; perhaps identical with slag 1
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Copper, steel, aluminum and precious metals can be recovered, but rare-earth metals typically fuse with other byproducts in waste called slag.
From The Wall Street Journal ● Jan. 23, 2026
He said it also makes steel recycling less polluting because making the chemicals currently used as slag has a high carbon cost too.
From BBC ● May 22, 2024
"We found the combination of cement clinker and iron oxide is an excellent steelmaking slag because it foams and it flows well," said Dunant.
From Science Daily ● May 22, 2024
The Cambridge team spotted the composition of used cement is almost exactly the same as the slag used in electric arc furnaces.
From BBC ● May 22, 2024
In one case the arsenic came from the slag heaps of mining operations, in the other from rock with a high natural content of arsenic.
From "Silent Spring" by Rachel Carson
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Lieberstein previously worked on "The Office" as one of its producers and as Toby, the bland HR representative everyone slagged off on.
From Salon ● Mar. 19, 2023
Executives who didn’t take her calls risked being slagged on Deadline.
From New York Times ● Jan. 21, 2023
"Anyone that we haven't slagged off," jokes Mica.
From BBC ● May 8, 2022
Anyway, you’ll be happy to hear, I fought through my misgivings and slagged the performance—but it struck me that if I was thinking about these questions in this context, these questions have permeated very deep.
From Slate ● Dec. 19, 2018
Hardly big enough so a cat could slip through, and under it is this big pile of coal slagged up against the foundation wall.
From "Freak The Mighty" by Rodman Philbrick
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He said: "No, we read Vanity Fair - they're slagging each other off in the pages... You don't need to go for lunch with those people."
From BBC ● May 26, 2023
“This is not about slagging anyone off in this TV series at all,” he said.
From Seattle Times ● Jul. 16, 2021
Fearn doesn’t share the inclination, saying, “I’ve never really been into slagging bands off. It’s just not my thing.”
From Washington Post ● Jan. 21, 2021
YouTube videos were dedicated to slagging her off.
From The Guardian ● Nov. 16, 2020
Gary Drake and Ross Wilcox might’ve been slagging me off, but the fainter the voices became, the less I wanted to go back.
From "Black Swan Green" by David Mitchell
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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.