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, that study also found a higher incidence of acute kidney injury, atrial fibrillation, and pulmonary embolism in those taking testosterone replacement therapy. — Alexander P. Cole, STAT, 18 July 2026

The hospital has also successfully used AI to analyze patients’ heart rhythms to tell whether someone could develop atrial fibrillation, a condition that can cause blood clots and strokes. — Clare Duffy, CNN Money, 16 July 2026

On May 27, the Queen was hospitalized and treated for heart failure and atrial fibrillation. — Meredith Kile, PEOPLE, 6 July 2026

Samsung already offers regulated features such as sleep apnoea detection and atrial fibrillation monitoring in various markets, while continuing work on more advanced technologies, including non-invasive continuous glucose monitoring. — David Phelan, Forbes.com, 25 June 2026

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