Titius is a lunar crater that is located , beyond the eastern limb. It lies to the west of the Lacus Solitudinis, a small lunar mare. Less than a crater diameter to the north east is the crater Bowditch, and farther to the southwest is Donner. The rim of this crater has been nearly ruined by subsequent impacts, leaving only the northern and northeast parts 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.