/ Dictionary / Index M muscle fiber: Meaning and Definition of Find definitions for: mus'cle fi"ber Pronunciation: [key] one of the structural cells of a muscle. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. musclebound muscleman Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language