cerebral aneurysm vs aneurism

cerebral aneurysm and aneurism both are nouns.

Word	Noun	Adjective	Verb	Adverb
cerebral aneurysm	Yes	No	No	No
aneurism	Yes	No	No	No

As nouns, aneurism is a hypernym of cerebral aneurysm; that is, aneurism is a word with a broader meaning than cerebral aneurysm:

cerebral aneurysm: an aneurysm of the carotid artery
aneurism: a cardiovascular disease characterized by a saclike widening of an artery resulting from weakening of the artery wall

Other hypernyms of cerebral aneurysm include aneurysm.

cerebral aneurysm (noun)	aneurism (noun)
an aneurysm of the carotid artery	a cardiovascular disease characterized by a saclike widening of an artery resulting from weakening of the artery wall