http://www.answers.com/library/Dictionary-cid-9086
(blīTH, blīth)
adj., blith·er, blith·est.
- Carefree and lighthearted.
- Lacking or showing a lack of due concern; casual: spoke with blithe ignorance of the true situation.
[Middle English, from Old English blīthe.]
blithely blithe'ly adv.
blitheness blithe'ness n.
Blithe can mean: Carefree/lighthearted, or casual/showing a lack of due concern.
He blithely spoke of the disaster as if it were a mere drop in the ocean.