noun,pluralpa·le·en·ceph·a·la[pey-lee-en-sef-uh-luh; especially British pal-ee-]. /ˌpeɪ li ɛnˈsɛf ə lə; especially British ˌpæl i-/.
(no longer in technical use) the more primitive part of the brain in the evolutionary development of animals, including all parts except the cerebral cortex and its related structures.