Open English Wordnet
Adjectives
(a)unconcernedlacking 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”
(s)unconcernedeasy in mind; not worried“the prisoner seems entirely unconcerned as to the outcome of the examination”