phan·er·o·ceph·a·la \-ˈsefələ\noun plural Usage: capitalized Etymology: New Latin, from phaner- + -cephala in some classifications: a division of Polychaeta distinguished by the well-developed prostomium corresponding to Errantia together with many Sedentaria • phan·er·o·ceph·a·lous\| ̷ ̷ ̷ ̷ ̷ ̷|sefələs\adjective