fiber

American  

[fahy-ber] / ˈfaɪ bər /

especially British, fibre

noun

1. a fine, threadlike piece, as of cotton, jute, or asbestos.

2. a slender filament.

   a fiber of platinum.

3. filaments collectively.

4. matter or material composed of filaments.

   a plastic fiber.

5. something resembling a filament.

6. an essential character, quality, or strength.

   people of strong moral fiber.

7. Botany.

   1. filamentous matter from the bast tissue or other parts of plants, used for industrial purposes.

   2. a slender, threadlike root of a plant.

   3. a slender, tapered cell which, with like cells, serves to strengthen tissue.

8. Anatomy, Zoology. a slender, threadlike element or cell, as of nerve, muscle, or connective tissue.

9. Also called bulk, dietary fiber, roughage.  Nutrition.

   1. the structural part of plants and plant products that consists of carbohydrates, as cellulose and pectin, that are wholly or partially indigestible and when eaten stimulate peristalsis in the intestine.

   2. food containing a high amount of such carbohydrates, as whole grains, fruits, and vegetables.

10. Chemistry. vulcanized fiber.

11. Optics. optical fiber.

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fiber British  

/ ˈfaɪbə /

noun

1. the usual US spelling of fibre

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fiber Scientific  

/ fī′bər /

1. The parts of grains, fruits, and vegetables that contain cellulose and are not digested by the body. Fiber helps the intestines absorb water, which increases the bulk of the stool and causes it to move more quickly through the colon.

2. One of the elongated, thick-walled cells, often occurring in bundles, that give strength and support to tissue in vascular plants. Fibers are one type of sclerenchyma cell.

3. Any of the elongated cells of skeletal or cardiac muscle, made up of slender threadlike structures called myofibrils.

4. The axon of a neuron.

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Other Word Forms

• fiberless adjective
• interfiber adjective

Etymology

Origin of fiber

1350–1400; 1970–75 fiber for def. 9; Middle English fibre (< Middle French ) < Latin fibra filament

Example Sentences

And here, Orsolya’s sincere if haphazard search for understanding, visible in every fiber of Tompa’s affecting central performance, cleverly lets Jude expose the insufficiency in quick fixes.

From Los Angeles Times • Apr. 3, 2026

In the wake of an anticipated fiber craze that is expected to trump last year’s protein-maxxing dietary fad, chia seeds have become all the rage.

From Salon • Mar. 31, 2026

In a simulated 9.3-km fiber link, the system reached a 3.2 Mbit/s secret key rate.

From Science Daily • Mar. 24, 2026

The optical cycle refers to general increases and decreases in demand for optical fiber, a core business for Corning.

From Barron's • Mar. 24, 2026

It’s like the dust in Mobius is woven into the fiber of every article of clothing that touches my skin.

From "Internment" by Samira Ahmed

Related Words

• grain
• thread
• tissue