adj. 25B6; adjective NONCHALANT, untroubled, unworried, unruffled, unconcerned, indifferent, blasé, heedless; relaxed, calm, equable, equanimous, serene, composed, easy, carefree, free and easy, happy-go-lucky, light-hearted; informal cool, laid-back.
INSOUCIANT
Meaning of INSOUCIANT in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012