unaccountable

unaccountable /ˌʌnəˈkaʊntəbəl/ adjective
unaccountable
/ˌʌnəˈkaʊntəbəl/
adjective
Britannica Dictionary definition of UNACCOUNTABLE
formal
1 
: not able to be explained : strange or mysterious
2 
a  : not required to explain actions or decisions — usually + to
b  : not required to be responsible for something — usually + for