Dellinger is a lunar crater that is located. It is attached to the southern rim of the crater Pannekoek. To the southeast lies the crater Marconi, and to the southwest is Chauvenet. The outer rim of this crater is eroded in places, including an outward protrusion along the southern rim and particularly along the northern half. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.