Mahasamadhi

Mahasamadhi (S): Great Meditative Equanimity.

The death, or dropping off of the physical body, of a great soul, an event occasioned by tremendous blessings. Also names the shrine in which the remains of a great soul are entombed. Mahasamadhi day names the anniversary of a great soul's transition.

Source

http://www.turtlehill.org/glos/m.html