decussation vs chiasma

decussation and chiasma both are nouns.

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

As nouns, decussation and chiasma are synonyms defined as:

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

Other synonyms of decussation include chiasm.

decussation (noun)	chiasma (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