mi·​cro·​or·​gan·​ism | \ ˌmī-krō-ˈȯr-gə-ˌni-zəm How to pronounce microorganism (audio) \

Definition of microorganism

: an organism (such as a bacterium or protozoan) of microscopic or ultramicroscopic size

Examples of microorganism in a Sentence

Recent Examples on the Web Brown materials have lots of carbon but not enough nitrogen to allow the microorganism to rapidly decompose them. Dan Gill, NOLA.com, "Turn icky leftovers and trimmings into compost, something that's good for your garden," 18 Nov. 2020 Think about a microorganism gathering to build a larger design. Joe Moore, Washington Post, "PS5 designer: ‘When I started drawing, it was much larger’," 9 Nov. 2020 And that slow play would have continued but for a fat little microorganism that traveled the globe earlier this year and disrupted everything. Sharon Carty, Car and Driver, "Car Buying is Changing and All It Took Was a Pandemic: The Enlightenment," 19 Sep. 2020 Citrus juice, vinegar or citric acid adds bite and makes the jam safer by inhibiting mold, bacteria and microorganism growth, while zest adds a floral note. Leena Trivedi-grenier, SFChronicle.com, "Capture the best of California's peaches in preserves, with a dose of revolution," 19 Aug. 2020 Interpreted strictly, that meant every microorganism in and on the space vehicle needed to be killed or otherwise removed. Matt Blitz, Popular Mechanics, "11,601 Swabs, 2,543 Wipes: How NASA Spent the Last 7 Years Protecting Mars from Humans," 30 July 2020 In their motion to dismiss, attorneys also pointed to microorganism and pollution exclusions in the contracts. Michael Braga, USA TODAY, "Minor league baseball teams the latest to sue insurance companies for failing to pay business interruption insurance," 9 July 2020 At its core, hydroxychloroquine, along with its close cousin chloroquine, is an antimalarial medication that primarily treats and prevents the mosquito-borne infection by killing the microorganism (a plasmodium parasite) that causes it. Popular Science, "Hydroxychloroquine isn’t the miracle COVID-19 treatment many hoped it would be," 29 May 2020 Sharpe has begun lending his stock of hydroxyl generators, which use ultraviolet light to kill microorganisms in the air, to local hospitals and homes for the elderly, where many are particularly vulnerable to COVID-19, the coronavirus disease. Chase Difeliciantonio, SFChronicle.com, "Workplace cleanliness a critical issue for businesses still operating in coronavirus era," 28 Mar. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'microorganism.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of microorganism

1880, in the meaning defined above

History and Etymology for microorganism

International Scientific Vocabulary

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Time Traveler for microorganism

Time Traveler

The first known use of microorganism was in 1880

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Statistics for microorganism

Last Updated

1 Dec 2020

Cite this Entry

“Microorganism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microorganism. Accessed 17 Jan. 2021.

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More Definitions for microorganism


How to pronounce microorganism (audio)

English Language Learners Definition of microorganism

biology : an extremely small living thing that can only be seen with a microscope


mi·​cro·​or·​gan·​ism | \ ˌmī-krō-ˈȯr-gə-ˌni-zəm How to pronounce microorganism (audio) \

Kids Definition of microorganism

: a living thing (as a bacterium) that can only be seen with a microscope


mi·​cro·​or·​gan·​ism | \ -ˈȯr-gə-ˌniz-əm How to pronounce microorganism (audio) \

Medical Definition of microorganism

: an organism of microscopic or ultramicroscopic size

More from Merriam-Webster on microorganism

Nglish: Translation of microorganism for Spanish Speakers

Britannica.com: Encyclopedia article about microorganism

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