У-87

HE моего (твоего и т. п. ) УМА ДЕЛО coll NP gen Invar subj-compl with бытье ( subj: это, abstr , or infin), pres only fixed WO

sth. is beyond s.o. 's ability to understand and/or does not concern s.o. : это не Х-ова ума дело X doesn't (wouldn't) understand it and it doesn't have anything to do with him anyway

(with the focus on s.o. 's inability to understand) X wouldn't understand (it) ift over X's head ift out of (beyond) X's depth (with the focus on sth Л not concerning s.o. ) it has nothing to do with X it's none of X's business (concern) not for X to know.

"А чего же ты слезу сронила?» — допытывалась любознательная старуха. «И чего вам, тетенька, надо? Не вашего ума дело!»(Шолохов 4). "What are you crying about then?" the inquisitive old woman persisted. "Don't bother me, Auntie! You wouldn't understand!" (4a).

«И за это получили из артиллерии?.. С бронепоезда?» - «Разумеется». - «Прискорбно. Достойно сожаления. Впрочем, это не нашего ума дело» (Пастернак 1). "So they were shelled?...From the armored train?" "Of course." "That's bad. All our sympathy. Still, it's none of our business" (1a).