fibrillation

noun

fi·​bril·​la·​tion ˌfi-brə-ˈlā-shən  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

However, high levels (over 4 g per day) of omega-3s have modestly increased the risk of atrial fibrillation in people with, or at risk for, cardiovascular disease.24 Omega-3s may also cause bad breath, heartburn, nausea, or diarrhea. —Megan Nunn, Verywell Health, 14 July 2025

City of Round Rock Virtual seminar on atrial fibrillation Feb. 19 If you have been diagnosed with atrial fibrillation, Baylor Scott & White is offering a free, virtual seminar to learn more about managing AFib. —Austin American Statesman, 2 July 2025

Mendelian randomization studies, which use genetic proxies to reduce confounding, have found that even light alcohol consumption increases the risk of hypertension, atrial fibrillation, stroke and heart failure. —Jesse Pines, Forbes.com, 21 Apr. 2025

One common example of an arrhythmia is atrial fibrillation (AFib), which begins in the upper chambers of the heart. —Melissa Rudy, FOXNews.com, 26 June 2025

Word History

First Known Use

1845, in the meaning defined at sense 1

Rhymes for fibrillation

• abdication
• aberration
• abjuration
• abnegation
• abrogation
• acceptation
• acclamation
• acclimation
• accusation
• activation
• actuation
• acylation

Medical Definition

fibrillation

noun

fi·​bril·​la·​tion ˌfib-rə-ˈlā-shən  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