chiasm

Definitions

  • WordNet 3.6
    • n chiasm an intersection or crossing of two tracts in the form of the letter X
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Webster's Revised Unabridged Dictionary
    • n Chiasm (Anat) A commissure; an intersection or crossing of two tracts; especially, the optic commissure, or crucial union of the optic nerves.
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Century Dictionary and Cyclopedia
    • n chiasm In anatomy, a decussation or intersection; specifically, the decussation of the optic nerves which occurs in nearly all vertebrates. See second cut under brain.
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Chambers's Twentieth Century Dictionary
    • n Chiasm kī′azm (anat.) a decussation or intersection, esp. that of the optic nerves—also Chias′ma
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Etymology

Webster's Revised Unabridged Dictionary
NL. chiasma, fr. Gr. chi`asma two lines placed crosswise, fr. to mark with a χ
Chambers's Twentieth Century Dictionary
Gr. chiasma, two lines crossed as in the letter X.