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A hint of the Greek word bios, meaning "life", can be seen in microbe. Microbes, or microorganisms, include bacteria, protozoa, fungi, algae, amoebas, and slime molds. Many people think of microbes as simply the causes of disease, but every human is actually the host to billions of microbes, and most of them are essential to our life. Much research is now going into possible microbial sources of future energy; algae looks particularly promising, as do certain newly discovered or created microbes that can produce cellulose, to be turned into ethanol and other biofuels.

Examples of microbe in a Sentence

Recent Examples on the Web
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This is where DeBenedictis’s as-yet-unannounced four other microbes come in. — Brian Gallagher, Scientific American, 2 Oct. 2026 The gut microbiome consists of trillions of bacteria, viruses and other microbes that populate human intestines. — Brenda Goodman, CNN Money, 1 Oct. 2026 In many cases, insects live symbiotically with these bacteria and experience no symptoms or adverse effects from the microbe’s presence. — New Atlas, 1 Oct. 2026 Jainism therefore strongly encourages ahimsa toward all living beings, from animals to microbes, and vegetarianism is the norm. — Encyclopedia Britannica, 30 Sep. 2026 See All Example Sentences for microbe

Word History

Etymology

International Scientific Vocabulary micr- + Greek bios life — more at quick entry 1

First Known Use

1878, in the meaning defined above

Time Traveler
The first known use of microbe was in 1878

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Cite this Entry

“Microbe.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microbe. Accessed 3 Oct. 2026.

Medical Definition

: microorganism, germ
—used especially of pathogenic bacteria
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