berry aneurysm
noun
ber·ry aneurysm
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Medical Definition of berry aneurysm
: an aneurysm of a cerebral artery that resembles a berry or sac in shape and typically occurs at an arterial junction in the circle of Willis
The culprit is a berry aneurysm, a slight (one-eighth to one-third of an inch) ballooning of the artery in the circle of Willis …— Tony Dajer, Discover, March 2009