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

Suppose a doctor needs to find the best and safest anticoagulant for a 68-year-old patient with atrial fibrillation and chronic kidney disease. —John Werner, Forbes.com, 8 Sep. 2025

Hypertension is the most prevalent and modifiable risk factor for the development of cardiovascular diseases such as coronary artery disease, heart failure, atrial fibrillation, stroke, chronic kidney disease, and all-cause mortality, Jones explained. —Sherri Gordon, Health, 29 Aug. 2025

High blood pressure is the leading risk factor for stroke and for several heart conditions, including coronary artery disease, heart failure and atrial fibrillation. —Stephanie Innes, AZCentral.com, 26 Aug. 2025

Hogan previously had leukemia and atrial fibrillation, an irregular heart rhythm, according to the medical examiner’s report that concluded the cause of death was natural. —Nino Paoli, Fortune, 21 Aug. 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