unaccountable
adjective uk/ˌʌn.əˈkaʊn.tə.bəl/ us/ˌʌn.əˈkaʊn.t̬ə.bəl/
(NOT RESPONSIBLE)
be unaccountable to someone/something 无须对…作出解释；不必对…负责
to not be expected to explain or provide a reason to a particular person or organization for your actions
The military and CIA hire contractors who are completely unaccountable to Congress. 军方和中央情报局雇佣承包商，这些人的行为完全不必对国会负责。
an unaccountable and inefficient bureacracy 不负责且效率低下的官僚体系
(SURPRISING)
难以解释的;无法理解的
not able to be explained or understood
For some unaccountable reason, he keeps his wallet in his underwear drawer. 不知何故，他把钱包放在内衣抽屉里。