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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

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Donoghue’s team found that LUCA had a metabolic pathway that is nearly identical to one found in modern microbes, known as the Wood-Ljungdahl pathway. — Yasemin Saplakoglu, Quanta Magazine, 12 Nov. 2026 It has long been assumed that this diverse population of microbes serves a role similar to the bacteria in our own bodies — helping the host while getting a home and a steady source of nutrition in return. — Neel Dhanesha, Vox, 11 Nov. 2026 One, Windfall Bio, uses microbes to digest methane into fertilizer. — Alex Cuadros, ProPublica, 10 Nov. 2026 When soil or other outside material sinks to the bottom of a lake, microbes consume oxygen to break it down, leading to the production of methane, a potent planet-heating gas. — Connie Hanzhang Jin, NPR, 8 Nov. 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 15 Nov. 2026.

Medical Definition

: microorganism, germ
—used especially of pathogenic bacteria
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