1. A slender, elongated, threadlike object or structure.
2. Botany One of the elongated, thick-walled cells that give strength and support to plant tissue.
a. Any of the filaments constituting the extracellular matrix of connective tissue.
b. Any of various elongated cells or threadlike structures, especially a muscle fiber or a nerve fiber.
a. A natural or synthetic filament, as of cotton or nylon, capable of being spun into yarn.
b. Material made of such filaments.
a. An essential element of a person's character: "stirred the deeper fibers of my nature" (Oscar Wilde).
b. Strength of character; fortitude: lacking in moral fiber.
6. Coarse, indigestible plant matter, consisting primarily of polysaccharides such as cellulose, that when eaten stimulates intestinal peristalsis. Also called bulk, roughage.
[French fibre, from Old French, from Latin fibra.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.