Definition of "crossing over" []

• The exchange of genetic material between homologous chromosomes that occurs during meiosis and contributes to genetic variability. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Franz Bäke and his battalion together with a battalion of armored personnel carriers to seize a crossing over the river."
• "With the roar of the outboard gone everything suddenly seemed preternatu-rally still, an illusion of serenity, as if by crossing over the underwater threshold they had entered a fantasy world of ice, had become one with the towering crystal palaces that surrounded them."
• "On crossing over to Lombock, separated from Bali by a strait less than twenty miles wide, I naturally expected to meet with some of these birds again; but during a stay there of three months I never saw one of them, but found a totally different set of species, most of which were utterly unknown not only in Java, but also in Borneo, Sumatra, and Malacca."