fibrillation
noun
fi·bril·la·tion
ˌfi-brə-ˈlā-shən 
ˌfī-
ˌfī-
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
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Other research has shown that people who received the shingles vaccine were 23 percent less likely to develop issues like heart attack, stroke, and atrial fibrillation than those who were unvaccinated.
—
Emily Kay Votruba, EverydayHealth.com, 22 Jan. 2026
My heart has an irregular rhythm, a condition known as atrial fibrillation that requires me to take the blood thinner Eliquis.
—Chicago Tribune, 18 Jan. 2026
Its electrophysiology products include devices used by electrophysiologists and interventional cardiologists for the treatment of cardiac arrythmias, such as atrial fibrillation.
—Kenneth Squire, CNBC, 17 Jan. 2026
World-first findings on coffee and irregular heartbeat University of Adelaide and University of California, San Francisco (UCSF) researchers led a randomized clinical trial of 200 adults from Australia, the US and Canada with atrial fibrillation (AF) to test coffee's impact on irregular heartbeats.
—New Atlas, 2 Jan. 2026
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Emily Kay Votruba, EverydayHealth.com, 22 Jan. 2026
My heart has an irregular rhythm, a condition known as atrial fibrillation that requires me to take the blood thinner Eliquis.
—Chicago Tribune, 18 Jan. 2026
Its electrophysiology products include devices used by electrophysiologists and interventional cardiologists for the treatment of cardiac arrythmias, such as atrial fibrillation.
—Kenneth Squire, CNBC, 17 Jan. 2026
World-first findings on coffee and irregular heartbeat University of Adelaide and University of California, San Francisco (UCSF) researchers led a randomized clinical trial of 200 adults from Australia, the US and Canada with atrial fibrillation (AF) to test coffee's impact on irregular heartbeats.
—New Atlas, 2 Jan. 2026
See All Example Sentences for fibrillation
Cite this Entry
“Fibrillation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fibrillation. Accessed 6 Feb. 2026.
Copy CitationMedical Definition
fibrillation
noun
fi·bril·la·tion
ˌfib-rə-ˈlā-shən
ˌfīb-
ˌfīb-
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
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