microorganism
/ˌmaɪkroʊˈɔrɡəˌnɪzəm/
noun
- A living thing that is too small to be seen without a microscope, such as a bacterium, virus, or fungus.
- Scientists use microscopes to study microorganisms in water and soil.
- Some microorganisms cause diseases, while others are essential for life.
- Yogurt contains beneficial microorganisms that help digestion.