Synonyms and related words :
airy, blase, blithe, breezy, buoyant, careless, contented, corky, debonair, easy, easygoing, feckless, free and easy, happy, happy-go-lucky, incautious, indifferent, insouciant, jaunty, light, light-hearted, lighthearted, lightsome, nonchalant, perky, reckless, resilient, unconcerned, unworried, wild