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

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

Key Takeaways In a recent survey of people with atrial fibrillation, more than 50 percent said cold foods and drinks at least sometimes triggered episodes. —Tom Gavin, EverydayHealth.com, 24 June 2025

Many wearables can also detect serious conditions like atrial fibrillation (AFib). —Emily Forlini, PC Magazine, 24 June 2025

Newsletter Sign up for our email newsletter for the latest science news There’s now data to back up the theory that stressful events like the loss of a loved one can change your heart’s physiology and contribute to atrial fibrillation, heart attacks, and stroke, among others. —Paul Smaglik, Discover Magazine, 15 May 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