chiasm vs decussation

chiasm and decussation both are nouns.

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

As nouns, chiasm and decussation are synonyms defined as:

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

Other synonyms of chiasm include chiasma.

chiasm (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