noun, na-adjective
very rude; outrageous; extremely insolent
Strongly negative term for behavior that is shockingly rude, insolent, or morally outrageous. Often used in formal or written contexts to express severe disapproval.
彼の不届き千万な態度には言葉もない。
I am speechless at his outrageously rude attitude.
そんな不届き千万な行為は許されない。
Such an extremely insolent act is unforgivable.
Compound of 不届き (rudeness, impropriety) and 千万 (extremely, myriad). The suffix 千万 intensifies the preceding word, creating a strong expression of condemnation.