Source : Webster's Revised Unabridged Dictionary (1913)

Unconcerned \Un`con*cerned"\, a.
   Not concerned; not anxious or solicitous; easy in mind;
   carelessly secure; indifferent; as, to be unconcerned at what
   has happened; to be unconcerned about the future. --
   {Un`con*cern"ed*ly}, adv. -- {Un`con*cern"ed*ness}, n.

         Happy mortals, unconcerned for more.     --Dryden.

Source : WordNet®

unconcerned
     adj 1: 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" [ant: {concerned}]
     2: easy in mind; not worried; "the prisoner seems entirely
        unconcerned as to the outcome of the examination"
     3: not occupied or engaged with; "readers unconcerned with
        style"