in·sou·ci·ant (ĭn-sōō'sē-ənt, āɴ'sōō-syäɴ') adj. Marked by blithe unconcern; nonchalant.
[French : in-, not (from Old French; see in-1) + souciant, present participle of soucier, to trouble (from Old French, from Vulgar Latin *sollicītāre, alteration of Latin sollicitāre, to vex; see solicit).] in·sou'ci·ant·ly adv.