Pocket Thesaurus
Antonyms of happy-go-lucky
cheerful, carefree, easygoing, blithe, casual, content, cool, devil-may-care, easy, feckless, free and easy, heedless, improvident, insouciant, irresponsible, lackadaisical, lighthearted, nonchalant, reckless, unconcerned, untroubled, carefree and untroubled, free-minded, living the life of Riley, without care
See this content immediately after install