# scum

/ˈskəm/ (US) · /skˈʌm/ (UK)

Source: https://englishreference.com/word/scum
Updated: 2026-06-20

## Senses

### 1. surface dirt

noun · CEFR B2

a layer of dirt, bubbles, or waste that forms on the surface of a liquid like water or soup.

For teachers: a layer of impurities, organic matter, or chemical waste that accumulates at the surface of a liquid.

- A thick green scum had formed on the surface of the abandoned pond.
- The industrial runoff resulted in a greyish scum coating the riverbanks, alarming local environmentalists about the water quality.

### 2. insult for people

noun · CEFR C1 · Informal · Slang · Vulgar

a very rude word for people you think are bad, dishonest, or have no morals.

For teachers: a highly derogatory collective or singular noun for individuals perceived as worthless, contemptible, or morally bankrupt.

- He called the people who stole from the charity 'absolute scum'.
- The tabloid press frequently refers to violent criminals as the scum of the earth to incite public indignation.

Usage: Often used as a collective noun without an 's' to refer to a group of people.

Teaching tip: This is a very strong and aggressive insult; students should be aware of its severity and generally avoid using it themselves.

### 3. to remove surface dirt

verb · CEFR C2 · Technical

to take the layer of dirt or waste off the top of a liquid.

For teachers: to remove the layer of impurities or froth from the surface of a liquid, such as molten metal or a cooking stock.

- The chef told his assistant to scum the boiling soup to keep the broth clear.
- In traditional metallurgy, the technician must carefully scum the molten lead to ensure the final casting is free of structural defects.

Usage: In modern cooking, 'skim' is much more common than 'scum'.

## Examples

- A thick green scum covered the surface of the pond.
- The detective looked at the criminals and told them they were the scum of the earth.
- Industrial runoff had left a chemical scum along the riverbank, while the local tabloids used the same word to describe the profiteers who owned the factory.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.