'Decussation' definitions:

Definition of 'decussation'

(from WordNet)
noun
An intersection or crossing of two tracts in the form of the letter X [syn: chiasma, chiasm, decussation]

Definition of 'Decussation'

From: GCIDE
  • Decussation \De`cus*sa"tion\, n. [L. decussatio.] Act of crossing at an acute angle, or state of being thus crossed; an intersection in the form of an X; as, the decussation of lines, nerves, etc. [1913 Webster]