acephaly vs acephalism

acephaly and acephalism both are nouns.

Word	Noun	Adjective	Verb	Adverb
acephaly	Yes	No	No	No
acephalism	Yes	No	No	No

As nouns, acephaly and acephalism are synonyms defined as:

acephaly and acephalism: absence of the head (as in the development of some monsters)

Other synonyms of acephaly include acephalia.

acephaly (noun)	acephalism (noun)
absence of the head (as in the development of some monsters)	absence of the head (as in the development of some monsters)