The Collaborative International Dictionary of English v.0.48:
Blitheness \Blithe"ness\, n. The state of being blithe. --Chaucer. [1913 Webster]WordNet (r) 3.0 (2006):
blitheness n 1: a feeling of spontaneous good spirits; "his cheerfulness made everyone feel better" [syn: cheerfulness, blitheness] [ant: cheerlessness, uncheerfulness]