The Collaborative International Dictionary of English v.0.48:

Atheling \Ath"el*ing\ ([a^]th"[e^]l*[i^]ng), n. [AS.
   [ae][eth]eling noble, fr. [ae][eth]ele noble, akin to G. adel
   nobility, edel noble. The word [ae][eth]el, E. ethel, is in
   many AS. proper names, as Ethelwolf, noble wolf; Ethelbald,
   noble bold; Ethelbert, noble bright.]
   An Anglo-Saxon prince or nobleman; esp., the heir apparent or
   a prince of the royal family. [Written also Adeling and
   [AE]theling.]
   [1913 Webster] Atheneum