[ kʌɪ'azmə , kɪ- ]
■ noun ( plural ~ta -tə )
1》 (also optic ~ ) 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.
Origin
C19: mod. L., from Gk ~ 'crosspiece, cross-shaped mark', from khiazein 'mark with the letter chi'.