Apis, in Egyptian mythology, a sacred bull thought to be an incarnation of Osiris, god of the underworld. For a bull to be an Apis, it had to be black and have a white triangle on the forehead, a half moon on the breast, and a small hump under the tongue in the shape of a scarab beetle (an emblem of immortality). When such a bull was found it was brought to Memphis, carefully tended, and, at its death, buried with elaborate ceremonies.