chiasma
|chi-as-ma|
/kaɪˈæzmə/
X-shaped crossing
Etymology
'chiasma' originates from Greek, specifically the word 'χίασμα' (chiasma), where the root 'χιάζω' (chiázō) meant 'to cross' or 'to shape like the letter chi (X)'.
'chiasma' passed into Late/Modern Latin as 'chiasma' and was borrowed into English (medical and biological usage) in the 19th century; the term came directly from Greek via New Latin.
Initially it meant 'a crossing' or 'cross-shaped mark'; over time it acquired specialized scientific senses such as the anatomical optic chiasm and the cytological point of chromatid crossover.
Meanings by Part of Speech
Noun 1
an X-shaped crossing of two structures or fibers, especially where optic nerves partially cross (the optic chiasm) or where nerve fibers decussate.
The optic chiasma is where some of the nerve fibers from each eye cross to the opposite side of the brain.
Synonyms
Noun 2
in genetics/cytology, the point at which two homologous chromatids exchange genetic material during crossing over (a chiasma is visible during meiosis).
During prophase I of meiosis, chiasmata form and mark sites of crossing over between homologous chromosomes.
Synonyms
Last updated: 2025/09/22 06:38