# pathogen

/ˈpæθədʒən/ (US) · /pˈæθədʒən/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/pathogen
Updated: 2026-05-08

## Definition

a tiny living thing that causes disease, such as a virus or bacteria.

For teachers: a bacterium, virus, or other microorganism that can cause disease in its host.

## Examples

- The new vaccine protects against several common pathogens.
- Hospital staff follow strict cleaning protocols to prevent the spread of dangerous pathogens between patients.
- The evolution of antibiotic resistance allows certain pathogens to survive treatments that were previously effective, posing a significant challenge to modern public health systems.

## Usage notes

- Commonly used in medical and scientific contexts to refer to any disease-causing agent.

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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.