chiasma vs decussation

chiasma and decussation both are nouns.

Word	Noun	Adjective	Verb	Adverb
chiasma	Yes	No	No	No
decussation	Yes	No	No	No

As nouns, chiasma and decussation are synonyms defined as:

chiasma and decussation: an intersection or crossing of two tracts in the form of the letter X

Other synonyms of chiasma include chiasm.

chiasma (noun)	decussation (noun)
an intersection or crossing of two tracts in the form of the letter X	an intersection or crossing of two tracts in the form of the letter X