fibrillation

noun

fi·​bril·​la·​tion ˌfi-brə-ˈlā-shən How to pronounce fibrillation (audio) ˌfī- How to pronounce fibrillation (audio)
1
: an act or process of forming fibers or fibrils
2
a
: a muscular twitching involving individual muscle fibers acting without coordination
b
: very rapid irregular contractions of the muscle fibers of the heart resulting in a lack of synchronism between heartbeat and pulse

Examples of fibrillation in a Sentence

Recent Examples on the Web
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Congestive heart failure was the most common complication, occurring in 36 percent of people, followed by atrial fibrillation (21 percent), cardiogenic shock (7 percent), stroke (5 percent), and heart attack (3 percent). Emily Kay Votruba, EverydayHealth.com, 15 May 2025 It's estimated that atrial fibrillation, the most common type of arrhythmia, will affect 12.1 million Americans by 2030. Simon Spichak, Health, 2 May 2025 The irregular heartbeat — ventricular fibrillation (v-fib) — prevents blood from pumping to the brain causing a person to faint or sudden cardiac death. Vanessa Etienne, People.com, 30 Apr. 2025 Higher doses of fish oil may increase the risk of atrial fibrillation. Amy Brownstein, Verywell Health, 6 May 2025 See All Example Sentences for fibrillation

Word History

First Known Use

1845, in the meaning defined at sense 1

Time Traveler
The first known use of fibrillation was in 1845

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Cite this Entry

“Fibrillation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fibrillation. Accessed 6 Jun. 2025.

Medical Definition

fibrillation

noun
fi·​bril·​la·​tion ˌfib-rə-ˈlā-shən How to pronounce fibrillation (audio) ˌfīb- How to pronounce fibrillation (audio)
1
: an act or process of forming fibers or fibrils
2
a
: a muscular twitching involving individual muscle fibers acting without coordination
b
: very rapid irregular contractions of the muscle fibers of the heart resulting in a lack of synchronism between heartbeat and pulse see atrial fibrillation, ventricular fibrillation

More from Merriam-Webster on fibrillation

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