To cross in the form of an X; to intersect or cross diagonally.
From Latin decussare, derived from decussis (the Roman numeral X), meaning to cross in the shape of an X. The verb entered English in scientific and anatomical contexts.
The optic nerves in your brain literally decuss—they cross over in an X shape called the optic chiasm, which is why each eye sends information to the opposite side of your brain!
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