/ Dictionary / Index C crossing over: Meaning and Definition of Find definitions for: cross'ing o'ver Pronunciation: [key] — Genetics. Genetics. the interchange of corresponding chromatid segments of homologous chromosomes with their linked genes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. crossing guard crossjack Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language