Open English Wordnet
Adjectives
(s)carefree, devil-may-care, freewheeling, happy-go-lucky, harum-scarum, slaphappycheerfully irresponsible“carefree with his money”, “freewheeling urban youths”, “had a harum-scarum youth”
(s)devil-may-care, raffish, rakishmarked by a carefree unconventionality or disreputableness“a cocktail party given by some … raffish bachelors” (Crary Moore)