decussation vs chiasm

decussation and chiasm both are nouns.

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

As nouns, decussation and chiasm are synonyms defined as:

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

Other synonyms of decussation include chiasma.

decussation (noun)	chiasm (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