[French : in-, not (from Old French; see in-1) + souciant, present participle of soucier, to trouble (from Old French, from Vulgar Latin *sollictre, alteration of Latin sollicitre, to vex; see solicit).]
insouciant – marked by blithe unconcern; “an ability to interest casual students”; “showed a casual disregard for cold weather”; “an utterly insouciant financial policy”; “an elegantly insouciant manner”; “drove his car with nonchalant abandon”; “was polite in a teasing nonchalant manner”
unconcerned – lacking in interest or care or feeling; “the average American…is unconcerned that his or her plight is the result of a complex of personal and economic and governmental actions…beyond the normal citizen’s comprehension and control”; “blithely unconcerned about his friend’s plight”
n-s
s
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nt, 
s
t
re, alteration of Latin sollicit
