insouciant

from WordNet (r) 3.0 (2006)

insouciant
    adj 1: 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" [syn: {casual}, {insouciant}, {nonchalant}]

from The Collaborative International Dictionary of English v.0.48

Insouciant \In`sou`ciant"\, a. [F.]
   Careless; heedless; indifferent; unconcerned. --J. S. Mill.
   [1913 Webster]