- blithe - lacking or showing a lack of due concern; "spoke with blithe ignorance of the true situation"
Antonym: concerned (indirect, via unconcerned)
- blithe, blithesome, lighthearted, lightsome - carefree and happy and lighthearted; "was loved for her blithe spirit"; "a merry blithesome nature"; "her lighthearted nature"; "trilling songs with a lightsome heart"
Antonyms: cheerless, uncheerful (indirect, via cheerful)