na-adjective, noun
outrageous; rude; unforgivable
Describes behavior that is morally or socially unacceptable, often implying a lack of consideration or respect. Used for actions that go beyond mere rudeness, suggesting a serious breach of decorum.
彼の不届きな態度には本当に腹が立った。
I was really angered by his outrageous attitude.
そんな不
Such reprehensible conduct is unforgivable.
Compound of 不 (fu, 'not') and 届き (todoki, the noun form of 届く 'to reach, to be delivered'), literally meaning 'not reaching' or 'not being delivered'. The sense of 'outrageous' or 'unforgivable' likely developed from the idea of failing to meet expected standards or duties.