/ Dictionary / Index C chiasma: Meaning and Definition of Find definitions for: chi•as•ma Pronunciation: (kī-az'mu), [key] — pl. -mas, -ma•ta a crossing or decussation, as that of the optic nerves at the base of the brain. a point of overlap of paired chromatids at which fusion and exchange of genetic material take place during prophase of meiosis. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: chiasma (Thesaurus) chiaroscuro chiasmatypy Related Content Daily Word Quiz: designate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language