Dictionary.com
definitions

dietary fiber

noun
  1. fiber(def 9).

Origin of dietary fiber

First recorded in 1975–80
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
dietary fiber in Medicine

dietary fiber

n.
  1. Coarse, indigestible plant matter, consisting primarily of polysaccharides, that when eaten stimulates intestinal peristalsis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.