umpteenth

"Umpteenth" is not a precise number. It is an informal word used for an extremely large, unspecified number in a series, especially when something has happened again and again. It usually suggests that the speaker has lost count or does not want to count anymore. The word is built to sound like an ordinal number, such as "tenth" or "twentieth," but it points only to the idea of "some very high number."

It is most often used with a touch of annoyance, exaggeration, or humor. For example, if someone says, "This is the umpteenth time I've had to explain this," they mean they have explained it many times already and are tired of repeating it. If you say, "She's on her umpteenth cup of coffee today," you mean she has had a great many cups, not that you know the exact number.

The word likely comes from the older slang term "umpty," which meant an unspecified number, plus the ending "-th," which is used in ordinal numbers. It is not a formal mathematical term, but it is common in everyday English. People use it to talk about repeated events, repeated complaints, or anything that feels as if it has happened far too many times. In short, "umpteenth" does not give a real count. It tells the listener, in a vivid and human way, that the number is high, unclear, and probably more than enough.