1. 
[syn: casual, insouciant, nonchalant]
The Collaborative International Dictionary of English v.0.48:
Insouciant \In`sou`ciant"\, a. [F.]
   Careless; heedless; indifferent; unconcerned. --J. S. Mill.
   [1913 Webster]
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]