/ Dictionary / Index M microsome: Meaning and Definition of Find definitions for: mi•cro•some Pronunciation: (mī'kru-sōm"), [key] — n. Cell Biol. a small inclusion, consisting of ribosomes and fragments of the endoplasmic reticulum and mitochondria, in the cytoplasm of a cell. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: microsome (Thesaurus) microsociology microspectrophotometer Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language