the less correct, but more popular, spelling of aneurysm (q.v.), by influence of words in -ism. The -y- is etymologically correct; the spelling with -i- suggests a meaning "nervelessness."
Entries linking to aneurism
aneurysm n.
"dilation of an artery," early 15c., from Medieval Latin aneurisma, from Greek aneurysmos "dilation," from aneurynein "to dilate," from ana "up" (see ana-) + eurynein "widen," from eurys "broad, wide" (see eury-). Related: Aneurysmal; aneurysmic.
-ism
word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.