/ Dictionary / Index M microfilament: Meaning and Definition of Find definitions for: mi•cro•fil•a•ment Pronunciation: (mī"kru-fil'u-munt), [key] — n. Cell Biol. a minute, narrow tubelike cell structure composed of a protein similar to actin, occurring singly and in bundles, involved in cytoplasmic movement and changes in cell shape. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. microfiche microfilaria Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language