# bacteria

/bækˈtɪɹiə/ (US) · /bæktˈiəɹɪɐ/ (UK)

Source: https://englishreference.com/word/bacteria
Updated: 2026-06-19

## Senses

### 1. microorganisms

noun · CEFR B2

tiny living things that can only be seen with a microscope.

For teachers: microscopic single-celled organisms that exist in diverse environments. Technically the plural of 'bacterium', though frequently used as a collective noun in non-scientific contexts.

- You should wash your hands to get rid of any harmful bacteria.
- The researchers identified several strains of bacteria in the soil that were capable of breaking down plastic waste.

Usage: Usually plural; takes a plural verb in formal and academic writing.

### 2. a lowlife person

noun · CEFR C2 · Slang · Vulgar

a very rude or unpleasant person who is treated with no respect.

For teachers: a derogatory term for a person or group of people perceived as socially or morally inferior.

- He treated the waiters like they were just bacteria.
- The corrupt official looked down on the protesters as if they were mere bacteria infecting his city.

Teaching tip: This is a highly offensive and dehumanising insult; learners should recognise it but avoid using it.

## Examples

- Washing your hands with soap helps remove harmful bacteria.
- The doctor prescribed a course of antibiotics to clear up the bacteria causing her throat infection.
- Because beneficial gut bacteria play a crucial role in digestion and immune function, prolonged antibiotic use can sometimes disrupt the body's natural microbiome balance.

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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.