As it can be read as 'feeding hungry ghosts' in the kun-doku (the word-for-word translating method from Chinese to Japanese), it means the rites to feed living things who fell into Gaki-do (world of hungry ghosts) specially after their death among Bonpu (unenlightened persons) in the worlds of Rokudo rinne (Rebirth in the Six Worlds) and holding a mass for their spirits.
訓読すれば「餓鬼に施す」と読めることからも分かるように、六道輪廻の世界にある凡夫の中でも、死後に特に餓鬼道に堕ちた衆生のために食べ物を布施し、その霊を供養する儀礼を指す。