Kolhörster is a lunar crater on the moon's far side. It lies about a crater-diameter to the south-southeast of the crater Kamerlingh Onnes, and to the northeast of the crater Michelson. To the south is an area marked with crater chains formed from secondary impacts during the creation of the Mare Imbrium impact basin. About one crater-diameter to the southeast is the Catena Leuschner crater chain, while further to the south is Catena Michelson. (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.