palaeencephalon
/ˌpalɪɛnˈsɛfəlɒn/ /ˌpeɪlɪɛnˈsɛfəlɒn/(also palaeëncephalon, paleencephalon, paleoencephalon) Chiefly Psychology
noun
A phylogenetically older portion of the vertebrate brain, as contrasted with the neencephalon.
Origin
Early 20th century. From German Palaeencephalon from palaeo- + Encephalon.