fibrillation

American  

[fib-ruh-ley-shuhn, fahy-bruh-] / ˌfɪb rəˈleɪ ʃən, ˌfaɪ brə- /

noun

1. the formation of fibrils, or fine fibers or filaments.

2. Pathology. uncontrolled twitching or quivering of muscle fibers, such as those of the heart.

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fibrillation British  

/ ˌfaɪbrɪˈleɪʃən, ˌfɪb- /

noun

1. a local and uncontrollable twitching of muscle fibres, esp of the heart, not affecting the entire muscle. Atrial fibrillation results in rapid and irregular heart and pulse rate. In ventricular fibrillation , the heart stops beating

2. irregular twitchings of the muscular wall of the heart, often interfering with the normal rhythmic contractions

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fibrillation Scientific  

/ fĭb′rə-lā′shən /

1. A rapid twitching of muscle fibers, as of the heart, that is caused by the abnormal discharge of electrical nerve impulses. Ventricular fibrillation is life-threatening.

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Etymology

Origin of fibrillation

First recorded in 1830–40; fibrillate + -ion

Compare meaning

How does fibrillation compare to similar and commonly confused words? Explore the most common comparisons:

• fibrillation vs. fasciculation

Example Sentences

For example, portfolio company Laminar, which developed a treatment for certain patients with the heart-rhythm disorder atrial fibrillation, was acquired by Johnson & Johnson in 2023, a down year for M&A, he said.

From The Wall Street Journal • Feb. 12, 2026

The positive result came after Bayer stopped a trial of the same drug to prevent stroke in patients with atrial fibrillation two years ago, because an existing treatment called apixaban performed better.

From MarketWatch • Nov. 24, 2025

The anticoagulant drugs and cardiac ablation procedures for treating atrial fibrillation aren’t without complication, so large studies are trying to determine if the additional arrhythmias found by devices like Zio are truly stroke threats.

From Barron's • Nov. 5, 2025

Atrial fibrillation is of particular concern because it causes irregular heartbeats and erratic blood flow, raising the risk of blood clots and stroke.

From Science Daily • Oct. 20, 2025

When he developed ventricular fibrillation, a heart rhythm abnormality that can be fatal within minutes, the problem was quickly fixed.

From "Class Matters" by The New York Times