hydranencephaly

noun
hy·​dran·​en·​ceph·​a·​ly | \ ˌhī-ˌdran-en-ˈsef-ə-lē How to pronounce hydranencephaly (audio) \
plural hydranencephalies

Medical Definition of hydranencephaly

: a congenital defect of the brain in which fluid-filled cavities take the place of the cerebral hemispheres