Definition of Cerebral aneurysm

Cerebral aneurysm: A localized widening of a blood vessel within the brain. An aneurysm is a localized widening (dilatation) of an artery or vein within the brain. At the area of an aneurysm, there is typically a bulge and the wall is weakened and may rupture. The word "aneurysm" comes from the Greek "aneurysma" meaning "a widening."

See: Berry aneurysm.