Named after Geminiano Montanari - Italian astronomer, mathematician (1633-1687).
Montanari is a lunar crater. It is located to the west-southwest of the prominent ray crater Tycho, and is attached to the southern rim of the walled plain Wilhelm. Along the northwestern side is the crater remnant Lagalla, and just to the south is the large walled plain Longomontanus. The rim has been so deeply eroded by impacts that it is now little more than an irregular border around 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.