/ Dictionary / Index M myofilament: Meaning and Definition of Find definitions for: my•o•fil•a•ment Pronunciation: (mī"u-fil'u-munt), [key] — n. Cell Biol. a threadlike filament of actin or myosin that is a component of a myofibril. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. myofibril myogenic Related Content Daily Word Quiz: braggart Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language