In Old Irish his name is spelled Oíngus or Óengus [oiŋɡus], from Proto-Celtic *oino- "one" and gus "strength" (or possibly "choice"). In Middle Irish this became Áengus, and in Modern Irish Aengus or Aonghus [ˈeːŋɡəsˠ], [ˈeːŋɣəsˠ]. Epithets include Óengus Óc/Aengus Óg ("Aengus the young"), Mac ind Óg ("son of the young"), Mac Óg ("young son") and Maccan.
Ler (meaning "Sea" in Old Irish; Lir is the genitive form) is a sea god in Irish mythology. His name suggests that he is a personification of the sea, rather than a distinct deity. He is named Allód in early genealogies, and corresponds to the Llŷr of Welsh mythology. Ler is chiefly an ancestor figure, and is the father of the god Manannán mac Lir.