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
Recent Examples on the Web
These structural changes in the heart muscle increase the risk of arrhythmias, especially atrial fibrillation.
—
Valerie Cacho, Verywell Health, 26 Feb. 2026
Women are at higher risk of stroke with the rhythm disorder atrial fibrillation than men, but women receive less blood-thinning and rhythm-control treatment than men.
—Elizabeth Cooney, STAT, 25 Feb. 2026
Other types included in the new report are heart failure, when the heart struggles to fill with and pump blood; atrial fibrillation, a type of abnormal heart rhythm; and stroke.
—Barbara Mantel, NBC news, 25 Feb. 2026
And the rates of numerous cardiovascular conditions, such as coronary disease, heart failure, stroke and atrial fibrillation could all rise slightly, according to the study.
—Lauren J. Young, Scientific American, 25 Feb. 2026
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Valerie Cacho, Verywell Health, 26 Feb. 2026
Women are at higher risk of stroke with the rhythm disorder atrial fibrillation than men, but women receive less blood-thinning and rhythm-control treatment than men.
—Elizabeth Cooney, STAT, 25 Feb. 2026
Other types included in the new report are heart failure, when the heart struggles to fill with and pump blood; atrial fibrillation, a type of abnormal heart rhythm; and stroke.
—Barbara Mantel, NBC news, 25 Feb. 2026
And the rates of numerous cardiovascular conditions, such as coronary disease, heart failure, stroke and atrial fibrillation could all rise slightly, according to the study.
—Lauren J. Young, Scientific American, 25 Feb. 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 12 Mar. 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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