mi·​crobe ˈmī-ˌkrōb How to pronounce microbe (audio)
microbial adjective
or less commonly microbic
microbially adverb

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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.

Example Sentences

Recent Examples on the Web In fact, scientists analyzed the microbes found on seven of da Vinci's drawings in 2020. Jennifer Ouellette, Ars Technica, 2 May 2023 See how Muslims celebrate Eid al-Fitr around the world 'The Odyssey' offers more than just monsters and magic Science How to see the Lyrid meteor shower at its peak Starship’s fiery crash was still a win for spaceflight These microbes found in tumors promote cancer. Animals, 20 Apr. 2023 Even with current initiatives to synthesize chemicals through biomanufacturing methods in microbes, their price point is still significantly higher than that of a complex organisms such as plants, which rely on photosynthesis. Melik Demirel, Forbes, 20 Apr. 2023 What’s more, odor-causing bacteria and microbes are unable to stick onto these wool fibers, so your socks and feet won’t get that nasty, sweaty stink. James Lynch, Popular Mechanics, 18 Apr. 2023 The icy shells of the ocean worlds may even contain pores filled with liquid water—and perhaps microbes, says Mike Malaska, an astrobiologist at NASA's Jet Propulsion Laboratory. Rebecca Boyle, Scientific American, 18 Apr. 2023 The microbes that cause these illnesses reservoir in mice where they can be picked up by young ticks taking their first bloodmeal. John Sass, Field & Stream, 11 Apr. 2023 The main ingredient of this milk was made by microbes in a lab, turned into tasty and recognizable food, and then served to a hungry reporter. Laura Reiley, Washington Post, 12 Mar. 2023 In simple terms, prebiotics feed or fuel the beneficial microbes that live on or in us. Good Housekeeping, 11 Mar. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'microbe.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Dictionary Entries Near microbe

Cite this Entry

“Microbe.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microbe. Accessed 28 May. 2023.

Kids Definition


mi·​crobe ˈmī-ˌkrōb How to pronounce microbe (audio)
microbial adjective
also microbic

Medical Definition


mi·​crobe ˈmī-ˌkrōb How to pronounce microbe (audio)
: microorganism, germ
used especially of pathogenic bacteria

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