noun
bacterium
A single-celled organism without a nucleus, belonging to a group found throughout the environment and in living things.
The microscope reveals a single bacterium in the prepared sample.
Etymology
Greek baktērion meant a small staff or rod. The biological name was inspired by rod-shaped organisms seen under magnification, although the group also includes organisms with other shapes.
More examples
- Many bacteria live harmlessly in the human body.
- The bacterium divided to form two cells.
- Scientists study how bacteria survive in extreme environments.
Forms
bacterium · bacteria
bacterial adjective — Relating to or caused by bacteria.