The Collaborative International Dictionary of English v.0.48:

Balder \Bal"der\ (b[add]l"d[~e]r), prop. n. [Icel. Baldr, akin
   to E. bold.] (Scan. Myth.)
   The most beautiful and beloved of the gods; the god of peace;
   the son of Odin and Freya. [Written also Baldur.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Balder
    n 1: (Norse mythology) god of light and peace and noted for his
         beauty and sweet nature; son of Odin and Frigg and husband
         of Nanna; killed by Hoth [syn: Balder, Baldr]