It’s apparently a sino-Japanese word, with the kanji 餓鬼. It literally means “hungry ghost”. What is a hungry ghost?
Apparently, it’s a concept comes from Hinduism/Buddhism, and it’s the Chinese translation of the Sanskrit word “preta”, “the Sanskrit name for a type of supernatural being described in Hinduism, Buddhism, Taoism, and Chinese folk religion as undergoing suffering greater than that of humans, particularly an extreme level of hunger and thirst”