To the northwest of this formation lies the crater Beaumont, while to the northeast is Rosse. The lava that formed Mare Nectaris also invaded this crater, so the structure now forms a bay-like extension. The remainder of the rim is heavily worn and covered in lesser impact craters, leaving little of the original rim intact. (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.