Named after John of Holywood, Johannes Sacrobuschus Sacrobosco - British astronomer, mathematician (c. 1200-1256).
Sacrobosco is an irregular lunar impact crater that is located in the rugged southern highlands to the west of the Rupes Altai escarpment. It is a readily identified feature due to the three circular craters that lie on its floor. The rim is heavily worn and eroded, especially in the northeast. The floor is flat in the south, except where overlain by Sacrobosco A and B, but is somewhat irregular in the northeast. (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.