From Longman Dictionary of Contemporary Englishumpteenthump‧teenth /ˌʌmpˈtiːnθ◂/ adjective [only before noun] if something happens for the umpteenth time, it happens again after having happened many times before – used when you are annoyed that it has happened so often ‘This is crazy, ’ she told herself for the umpteenth time.
Examples from the Corpus
for the umpteenth time• They're showing "The Wizard of Oz" for the umpteenth time.• The blonde hostess leaned across him to re-charge his glass for the umpteenth time.• They just weren't compatible, she told herself for the umpteenth time.• This is crazy, she told herself for the umpteenth time.• You did the wise thing, calling a halt when you did, she told herself sharply for the umpteenth time.• You may find your temper on a short fuse when confronting your child or teenager for the umpteenth time.• One day, when he catches me reading for the umpteenth time, he comes up to me after class, exasperated.• Turning away for the umpteenth time, she gave a little frustrated sigh.• I'd introduce you to my wife, but she's disappeared for the umpteenth time this evening.Origin umpteenth (1900-2000) umpty “many” (a joke word) ((1900-2000)) + -teenth (as in thirteenth) 