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

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Other microorganisms like fungi are also part of this environment. Cassie Shortsleeve, SELF, "Is Bar Soap Sanitary or Just Crawling With Germs?," 5 Apr. 2019 Ice cubes and lemon juice: Many of us think that the ice in our drinks is safe and that the acid from a lemon slice dropped in a beverage reduces any contaminating microorganisms. Paul Dawson And Brian Sheldon, WSJ, "The Myths of Microbe-Fighting," 9 Nov. 2018 These microorganisms are usually harmless, Elitza Theel, Ph.D., a microbiologist in the laboratory medicine and pathology department at the Mayo Clinic in Rochester, Minnesota, tells SELF. Jessica Toscano, SELF, "Here's How Often You Should Really Clean Your Yoga Mat," 12 Apr. 2019 Belly buttons contain a lot of folds that allow for the buildup of dead skin cells, sweat, and various microorganisms, Cynthia Bailey, M.D., a diplomate of the American Board of Dermatology and founder of Dr. Bailey Skin Care, tells SELF. Korin Miller, SELF, "5 Belly Button Infections You Can Get (and What to Do If You Have One)," 23 Feb. 2019 Assuming something as relatively benign as submarine-detecting microorganisms, does any country have the right to spread synthetic organisms—particularly those with military purposes—in international waters? Kyle Mizokami, Popular Mechanics, "The Military Wants to Create Synthetic Life Forms to Track Enemies," 4 Dec. 2018 This important balance of microorganisms is also known as your skin microbiome. Jessica Toscano, SELF, "Here’s How Often You Should Really Be Washing Your Sheets," 23 Feb. 2019 The curators liken his frames to stem cells, which can regenerate into different kinds of microorganisms. Lane Florsheim, WSJ, "130,000 Andy Warhol Photos, Once Unknown, Debut in a New Exhibition in California," 27 Sep. 2018 But equally important is how the off-earth environment impacts the microorganisms in our bodies and all around us. John Wenz, Popular Mechanics, "Living in Space Doesn't Turn Bacteria into Killer Superbugs, Study Says," 9 Jan. 2019

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

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Last Updated

18 May 2019

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Time Traveler for microorganism

The first known use of microorganism was in 1880

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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

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Britannica.com: Encyclopedia article about microorganism

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using a distributed computer network

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