insouciant

1 having or showing freedom from worries or trouble the insouciant gaiety of the idle rich Synonyms blithe, debonair, devil-may-care, gay, happy-go-lucky, carefree, lighthearted, lightsome, slaphappy, unconcernedRelated Words blasé (also blase), breezy, cavalier, nonchalant; casual, easygoing, informal, laid-back, low-pressure, relaxed, unfussyNear Antonyms earnest, grave, serious, serious-minded, somber (or sombre); careful, cautious, heedful, wary; anxious, concerned, upset, worried; long-suffering, overburdened, sorrowfulAntonyms careworn

2 having or showing a lack of interest or concern an insouciant attitude about punctuality that is really discourteous to her coworkers Synonyms apathetic, casual, complacent, disinterested, incurious, insensible, indifferent, nonchalant, perfunctory, pococurante, unconcerned, uncurious, uninterestedRelated Words halfhearted, lukewarm, tepid; aloof, cold, numb, remote, unemotional; callous, hard-hearted, insensitive, unfeeling; calm, cool, detached, dispassionate; careless, heedless, mindless; impassive, impervious, phlegmatic, stoic (or stoical), stolid; lethargic, listless; unimpressedNear Antonyms attentive, aware, conscientious, heedful, mindful; caring, sensitive, warmhearted; ardent, fervent, keen, passionate, warm, zealousAntonyms concerned, interested