fi·ber | \ˈfī-bər \

Definition of fiber 

1 : a thread or a structure or object resembling a thread: such as

a(1) : a slender root (as of a grass)

(2) : an elongated tapering thick-walled plant cell void at maturity that imparts elasticity, flexibility, and tensile strength

b(1) : a strand of nerve tissue : axon, dendrite

(2) : one of the filaments composing most of the intercellular matrix of connective tissue

(3) : one of the elongated contractile cells of muscle tissue

c : a slender and greatly elongated natural or synthetic filament (as of wool, cotton, asbestos, gold, glass, or rayon) typically capable of being spun into yarn

d : mostly indigestible material in food (such as legumes, whole grains, and vegetables) that stimulates the intestine to peristalsis and promotes elimination of waste from the large intestine : bulk, roughage dietary fiber trying to get more fiber in her diet

2 : material made of fibers especially : vulcanized fiber

3a : an element that gives texture or substance

b : basic toughness : strength, fortitude

c : essential structure or character the very fiber of a person's being

Keep scrolling for more

Other Words from fiber

fibered \ˈfī-bərd \ adjective

Examples of fiber in a Sentence

It's important to get enough fiber in your diet. What foods do you recommend as good sources of fiber? foods that are high in fiber The fabric is made from a mix of synthetic fibers. The natural fibers allow the fabric to breathe. The paper is made from both cotton and wood fiber. Nylon is a very strong man-made fiber. The police examined hair and bits of fiber found in the victim's car.
See More

Recent Examples on the Web

The County Department of Public Works staff will advise people about how to protect their properties, homes, garages, sheds and other structures and provide free sand, sandbags, fiber rolls and items to stabilize properties before rains arrive. Linda Mcintosh,, "Lions Club member receives fellowship award news," 14 July 2018 The other five finalists - Erick Antonio Benitez, Sutton Demlong, Nate Larson, Stephen Towns – all from Baltimore - and Eunice Park, from Parkville- have work in various mediums including sculpture, paintings and fiber arts. Katie V. Jones, Howard County Times, "Laurel photographer's perceptions of beauty," 12 July 2018 Fiona is featured in a quilt and fiber art show at The Barn in Mariemont through July 1. Jennie Key,, "You have to see how cute the Fiona snow globe is," 11 July 2018 Some fiber originally sold to China was redirected to Vietnam. Fortune, "China Cancels U.S. Soybean Purchases as Trade War Takes Hold," 6 July 2018 Sheah Rarback A recent article in Molecular Nutrition and Food Research compared mangos with fiber for relief of constipation. Sheah Rarback, miamiherald, "Ubiquitous mangos taste good - and are good for you, too," 29 June 2018 Fast-forwad to the social media age, and the look has reappeared on the runway of Chanel Resort 2019, where jeans and capris artfully revealed their fibers from thigh to hem. Liana Satenstein, Vogue, "Are Trashy-Chic, Extreme Ripped Jeans Officially Back?," 21 June 2018 Exterior siding made with wood products such as boards, panels or shingles are also suggested to be replaced with ignition resistant building materials such as stucco, fiber cement, wall siding, fire retardant or treated wood. Julie Gallant, Ramona Sentinel, "Fire readiness begins with property checks, new fire truck," 21 June 2018 The researchers can tune the distance by increasing or decreasing the tension in the fiber. Chris Lee, Ars Technica, "Spinning glass ball rejects light from one direction," 27 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fiber.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of fiber

1607, in the meaning defined at sense 1

History and Etymology for fiber

Middle French fibre, from Latin fibra

Keep scrolling for more

Learn More about fiber

Dictionary Entries near fiber

fiat money





fiber box

fiber can

Phrases Related to fiber

with every fiber of one's being

Statistics for fiber

Last Updated

14 Oct 2018

Look-up Popularity

Time Traveler for fiber

The first known use of fiber was in 1607

See more words from the same year

Keep scrolling for more

More Definitions for fiber



English Language Learners Definition of fiber

: plant material that cannot be digested but that helps you to digest other food

: a thin thread of natural or artificial material that can be used to make cloth, paper, etc.

: material (such as cloth) that is made from thin threads : something made of fibers


fi·ber | \ˈfī-bər \

Kids Definition of fiber

1 : a thread or a structure or object resembling a thread

2 : plant material that cannot be digested


variants: or chiefly British fibre \ˈfī-bər \

Medical Definition of fiber 

1 : a thread or a threadlike structure or object: as

a : a strand of nerve tissue : axon, dendrite

b : one of the filaments composing most of the intercellular matrix of connective tissue

c : one of the elongated contractile cells of muscle tissue

2 : mostly indigestible material in food that stimulates the intestine to peristalsis

called also bulk, dietary fiber, roughage

Keep scrolling for more

Comments on fiber

What made you want to look up fiber? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
Spell It

Can you spell these 10 commonly misspelled words?

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!