unaccountable
adj
1 that cannot be explained or accounted for 無法解釋的; 難以說明的
an unaccountable increase in cot deaths, ie of babies 難以解釋的嬰兒猝死數量上升的現象
For some unaccountable reason, the letter never arrived. 不知何故, 那封信始終未收到.
2 ~ (to sb/sth) (fml 文) not answerable for one's actions, etc; not accountable (對自己的行為等)不必負責任的, 無責任的.