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chiasma

Pronunciation: /kʌɪˈazmə, kɪ-/

Definition of chiasma

noun (plural chiasmata /-tə/)

  • 1 (also optic chiasma) Anatomy the X-shaped structure formed at the point below the brain where the two optic nerves cross over each other.
  • 2 Biology a point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.

Origin:

mid 19th century: modern Latin, from Greek chiasma 'crosspiece, cross-shaped mark', from khiazein 'mark with the letter chi'

chiasma in other Oxford dictionaries

Definition of chiasma in the US English dictionary