Zelinsky is a lunar crater on the far side. It lies nestled along the northern edge of Mare Ingenii, with the oddly shaped crater Van de Graaff along the east rim and the lava-flooded crater Thomson within one crater diameter to the south. This crater is somewhat elliptical, having an outwardly bulging rim to the east. Many parts of the rim have not been significantly eroded by impacts, although a small crater lies along the inner wall at the north end of the interior floor. (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.