anencephalicPronunciation: /ˌanɛnsɪˈfalɪk, -kɛˈfalɪk/ MedicineDefinition of anencephalic adjective having part or all of the cerebral hemispheres and the rear of the skull congenitally absent. noun an anencephalic fetus or infant. Derivatives anencephaly noun Origin: mid 19th century: from Greek anenkephalos 'without brain' + -icanencephalic in other Oxford dictionaries Definition of anencephalic in the US English dictionary