/ Dictionary / Index M mesosome: Meaning and Definition of Find definitions for: mes•o•some Pronunciation: (mez'u-sōm", mes'-, mē'zu-, -su-), [key] — n. the anterior portion of the abdomen in arachnids. a whorled structure extending inward from the cell membrane in Gram-positive bacteria and containing enzymes for cellular respiration. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mesoscale mesosphere Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language