neocortex Syllabification: (ne·o·cor·tex)Pronunciation: /ˌnēōˈkôrteks/Definition of neocortex noun (plural neocortices /-ˈkôrtiˌsēz/) Anatomy a part of the cerebral cortex concerned with sight and hearing in mammals, regarded as the most recently evolved part of the cortex. Derivatives neocorticalPronunciation: /-ˈkôrtikəl/ adjective neocortex in other Oxford dictionaries Definition of neocortex in the British & World English dictionary