bacteria
noun
plural of bacterium
Note: Microscopic single-celled organisms lacking a distinct nucleus are known as bacteria. They may be shaped like spheres, rods, or spirals. They inhabit virtually all environments, including soil, water, organic matter, and the bodies of animals. Many bacteria swim by means of long whiplike structures called flagella. The DNA of most bacteria is found in a single, circular chromosome, and is distributed throughout the cytoplasm rather than contained within a membrane-enclosed nucleus. Though some bacteria can cause food poisoning and infectious diseases in humans, most are harmless and many are beneficial. They are used in various industrial processes, especially in the food industry (for example, in the production of yogurt, cheeses, and pickles).
About Viruses and Bacteria: Usage Guide
Viruses differ from bacteria in several important ways. Viruses are not living organisms; they can only replicate in the cells of a host. By contrast, bacteria are single-celled organisms that can reproduce on their own and are many times larger than viruses. While both viruses and bacteria can cause disease, most bacteria are harmless and many are beneficial.
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“Bacteria.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/bacteria. Accessed 10 Nov. 2026.
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