not occupied or engaged with "readers unconcerned with style"
easy in mind
not worried "the prisoner seems entirely unconcerned as to the outcome of the examination"
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"