: a small filament or fiber: such as
a
b(1)
: one of the fine threads into which a striated muscle fiber can be longitudinally split
(2)
Examples of fibril in a Sentence
Recent Examples on the Web
Alzheimer’s has long been linked to harmful tau protein fibrils that build up in the brain and interfere with cognitive function, but researchers have now discovered soft, small clusters that appear first.
—
Melissa Rudy,
FOXNews.com,
18 Nov. 2025
Cryo-electron microscopy has now uncovered fibrils of an unexpected protein.
—
Big Think,
24 June 2024
This diagram shows how gold ions adhere to a sponge of protein fibrils, in order to separate the gold from other elements.
—
IEEE Spectrum,
14 Mar. 2024
Five of these helices wind together to make up a microfibril, and thousands of microfibrils gather to form a fibril.
—
Ed Yong,
Discover Magazine,
15 June 2011
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Melissa Rudy,
FOXNews.com,
18 Nov. 2025
Cryo-electron microscopy has now uncovered fibrils of an unexpected protein.
—
Big Think,
24 June 2024
This diagram shows how gold ions adhere to a sponge of protein fibrils, in order to separate the gold from other elements.
—
IEEE Spectrum,
14 Mar. 2024
Five of these helices wind together to make up a microfibril, and thousands of microfibrils gather to form a fibril.
—
Ed Yong,
Discover Magazine,
15 June 2011
Cite this Entry
“Fibril.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fibril. Accessed 5 Jul. 2026.
Copy CitationMedical Definition
: a small filament or fiber: as
a
: one of the fine threads into which a striated muscle fiber can be longitudinally split
b
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