an·​aer·​o·​bic | \ˌa-nə-ˈrō-bik; ˌan-ˌer-ˈō-\

Definition of anaerobic 

1a : living, active, occurring, or existing in the absence of free oxygen anaerobic respiration anaerobic bacteria

b : of, relating to, or being activity in which the body incurs an oxygen debt anaerobic exercise

2 : relating to or induced by anaerobes

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Other Words from anaerobic

anaerobically \ -​bi-​k(ə-​)lē \ adverb

Did You Know?

In Greek, the prefix a- or an- means "not" or "without", and bios means "life". Anaerobic sports and exercise, such as gymnastics, weight lifting, and sprinting, are of high intensity but short duration, so they don't involve much oxygen intake. Anaerobic exercise triggers a different type of cell activity from aerobic exercise. As a result, it doesn't do much for your heart and lungs and it doesn't burn off fat; what it does do is build muscle. Anaerobic bacteria are bacteria that live without oxygen. They're responsible for several nasty conditions, including tetanus, gangrene, botulism, and food poisoning. They often live in deep wounds, so a bad dog bite—or, even worse, a human bite—can be dangerous, since the mouth is full of anaerobic bacteria. But most anaerobic bacteria are harmless, and many are essential to our lives.

Examples of anaerobic in a Sentence

Weight lifting is an anaerobic exercise. Some bacteria are aerobic and others are anaerobic.

Recent Examples on the Web

The animal waste in the lagoons undergoes anaerobic digestion, where microorganisms break down many of the substances into carbon dioxide and methane. Umair Irfan, Vox, "Florence dropped so much rain that hog waste is spilling out of lagoons," 18 Sep. 2018 In fact, the digester Porter wants to build won’t be much different from devices sold on the Internet: A large tank that can hold water, human waste and anaerobic bacteria will produce fertilizer and methane gas to power cooking stoves and fires. Cleve R. Wootson Jr., The Seattle Times, "Mount Everest is a ‘fecal time bomb.’ Here’s one man’s idea for handling 14 tons of human waste.," 7 Aug. 2018 Weight lifting is an anaerobic exercise, meaning your body relies on the strength within its muscles more than oxygen while completing the exercise. Michael Yang,, "Q&A: How tough is tough enough for strength training?," 10 Apr. 2018 This helps eliminate risk of anaerobic bacteria growth. Bonnie S. Benwick, charlotteobserver, "What you should know about buying frozen fish," 3 July 2018 DeFeo said the Temple sewage should be going to a facility equipped with biogas cogeneration, an anaerobic process in which methane in sewage is made into fuel, making the initiative sustainable. Annabelle Williams,, "Temple's food waste digesters disrupting the industry or just 'shifting the burden'?," 27 June 2018 The renewable energy package also includes 1.6 megawatts generated by an anaerobic digestion project in Southington. Stephen Singer,, "State Taps First-Ever Offshore Wind Power In Clean Energy Program," 13 June 2018 Prior research has demonstrated SIT can improve both the aerobic and anaerobic metabolism., "Optimum Performance: SIT your way to better performance," 16 Mar. 2018 The anaerobic digester annually converts 500 tons of animal manure and other organic waste into methane-rich gas to help power the zoo's animal hospital, leaving a nutrient-rich fertilizer as a byproduct. Elissa Robinson, Detroit Free Press, "Detroit Zoo is giving away free buckets of poop," 3 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'anaerobic.' 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 anaerobic

1877, in the meaning defined at sense 1a

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Last Updated

15 Nov 2018

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The first known use of anaerobic was in 1877

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English Language Learners Definition of anaerobic

of exercise : strengthening muscles by forcing them to work very hard for a brief time

: not using oxygen


an·​aer·​o·​bic | \ˌan-ə-ˈrō-bik; ˌan-ˌa(-ə)r-ˈō-, -ˌe(-ə)r- \

Medical Definition of anaerobic 

1a : living, active, or occurring in the absence of free oxygen during heavy exercise anaerobic respiration occurs, pyruvic acid acts as a hydrogen acceptor, and lactic acid builds up in the tissues anaerobic bacteria

b(1) : of, relating to, or being activity in which the body incurs an oxygen debt an anaerobic workout Anaerobic activities like sprinting and weight lifting, on the other hand, burn carbohydrates without using oxygen …— Jane E. Brody, The New York Times, 28 Sept. 1986

(2) : of or relating to the body's ability to incur an oxygen debt Your anaerobic threshold is basically how long you can last without breathing (your lungs working in oxygen debt) while, say, sprinting or going as hard as you can on a bike or in the pool.— Bob Condor, The Seattle Post-Intelligencer, 22 Sept. 2008

2 : relating to or induced by anaerobes

Other Words from anaerobic

anaerobically \ -​bi-​k(ə-​)lē \ adverb

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Britannica English: Translation of anaerobic for Arabic Speakers

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to clear from alleged fault or guilt

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