Definition of "atheling"

[…] to substitute as the Confessor′s heir, the Atheling Edward (son of Edmund Ironside), who was then an exile in Hungary. After the atheling′s return from exile, and his very suspicious death in England in 1057, the Norman duke must surely have realized that his chief opponent in England was likely to be Harold Godwineson […] .

1966, Dorothy Whitelock, The Norman Conquest, New York: Charles Scribner's Sons, page 60