Wiktionary
n. (context chiefly US English) (alternative form of wits' end English)
Wikipedia
'Wit's End' is the fifth full-length album by Cass McCombs. It was released on Domino Records in April 2011, becoming the first of two albums released by McCombs that year. The first single from the album, "County Line", was accompanied by two different music videos.
Usage examples of "wit's end".
A trader, who did not sell opium, confessed to me that he was at his wit's end.
Heating without melting, dry at the center, a pile of sand, no man, no success, no fault, she had thrown the wands in the ancient game of Bioka, always resorted to when she was at her wit's end, and the wands said no fault, correction in order, all is not right at the Sinter.
The poor youngsters were at their wit's end, trying to find something to distract me with!
These two conditions seemed so conflicting that Bramah was almost at his wit's end, and for a time despaired of being able to bring the machine to a state of practical efficiency.
My guide stopped and looked about her like one who is at her wit's end.