fibrillation

Etymology

It is formed from English fibrillate + -ation.^[2][3][4][5] The verb is formed from New Latin fibrilla (“a little fibre, filament”) and -ate,^[2][3][6] the Latin noun being a diminutive of fibra (“fibre, filament; entrails”),^[3] which also gave English fibril and fiber.^[3][2] Etymonline calls fibra of uncertain origin, perhaps related to filum (“a thread”) or to findō (“to split”).^[3]

Earliest recorded meaning

The process of becoming fibrillated, or arrangement into fibrils: first recorded in Todd's Cyclopaedia of Anatomy and Physiology (1839–47).^[2] Dictionary.com dates the word to 1830–40,^[5] Etymonline to 1842,^[3] and Merriam-Webster Unabridged to 1845.^[6]

Semantic evolution

The medical sense, a quivering of the fibrils of a muscle or nerve, especially those of the heart, appears in 1882, in Quain's Dictionary of Medicine,^[2][3] and it causes the heart to beat irregularly.^[3] The verb fibrillate was used of heart muscle from 1910.^[2] Medical writers distinguish the twitching of single muscle fibres, which does not move the muscle as a whole, from the fast irregular contractions of the heart's chambers:^[7][8] in atrial fibrillation the heartbeat and pulse become rapid and irregular, and in ventricular fibrillation the heart stops beating.^[8] In 20th-century paper-making the word was applied to the beating of vegetable fibres until they split into fibrils, first in 1929.^[2]

Timeline

• 1839 – arrangement into fibrils; the process of becoming fibrillated.^[2]
• 1882 – a quivering of the fibrils of a muscle, especially of the heart.^[2][3]
• 1929 – in paper-making, the splitting of fibres into fibrils.^[2]

Meanings

Noun

1. Very rapid, irregular contractions of the muscle fibres of the heart, so that the heartbeat and the pulse are no longer in step.^[6][8][7]
2. Uncontrolled twitching of individual muscle fibres, not of the muscle as a whole.^[8][6][7]
3. The formation of fibrils, or the state of being made of fibrils.^[6][2][7]
4. In paper-making, the beating of fibres so that they split into fibrils.^[2][6]

Word family

• ventricular fibrillation
• auricular fibrillation

Related words

• fiber
• fibrillate
• defibrillate
• defibrillator
• fibril

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h i Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b c d Stedman's Medical Dictionary, Baltimore: Lippincott Williams & Wilkins
8. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins