chromatid

Japanese: chromatid

...When cells undergo meiosis, from pachytene to metaphase I, the paired homologous chromosomes split longitudinally along their long axes to form a total of four chromatids (a in the figure), but there are areas where these four chromatids exchange partners to form an X-shape (b in the figure). These areas are called chiasmas.

From [Chromosomes]

… From the S phase to the metaphase of somatic cell division, chromosomes have a double structure because DNA replication is complete but chromosome separation has not yet occurred. Each half of the double structure of chromosomes at this stage is called a chromatid. This double structure becomes evident with an optical microscope at the end of prophase. …

*Some terminology explanations that mention "chromatid" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…細胞が減数分裂を行う際に太糸期から第1分裂中期にかけて，対合した相同染色体は，長軸に沿って縦裂し計4本の染色分体chromatidとなる(図のa)が，この4本の染色分体の間で互いに相手を交換してX字型を呈する部位がみられる(図b)。この部位をキアズマという。…