aneurysm n.

before vowels an-, word-forming element meaning: 1. "upward, up in place or time," 2. "back, backward, against," 3. "again, anew," from Greek ana (prep.) "up, on, upon; up to, toward; throughout; back, backwards; again, anew," from an extended form of PIE root *an- (1) "on, upon, above" (see on, which is the English cognate). In old medical prescriptions, ana by itself meant "an equal quantity of each."

word-forming element meaning "wide," from Greek eurys "broad, wide," from PIE root *were- (1) "wide, broad" (source also of Sanskrit uruh "broad, wide").

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."