A festival held by Asoka in honour of the Buddha when Māhakāla created for him a figure of the Buddha. The festival lasted for seven days (Mhv.v.94).
The Mahāvamsa Tīkā explains it by saying that the king fasted for seven days, standing gazing at the figure with unwinking eyes. But even at the time of the Tīkā there seems to have been uncertainty regarding the meaning of the word. See MT.209f.