(idiomatic) A point in time which is nearly too late; the last minute.
(idiomatic, usually hyphenated) Used attributively.
Origin of eleventh-hour
King James Bible, Matthew 20:6:
Eleventh-hour Sentence Examples
The latter at the last moment recorded their votes in favor of the Abarzuza Bill when they perceived that a strange sort of eleventh-hour presentiment was about to make all the Spanish parties vote this insufficient reform.
However, at the eleventh hour the government snatched victory from the jaws of defeat.
At the eleventh hour he summoned Guillaume to his help against the overwhelming forces of the Saracens.
That day was also the last on which any hope remained of the Sari Bair offensive accomplishing its purpose, and on which help from Suvla might conceivably even at the eleventh hour have turned the scale.
His eleventh-hour conversion could not avert the conflict of interests which led to the war of 1904-5, from which Russia emerged defeated, but enabled him to veil a serious diplomatic error by relinquishing the odium of failure to his successor, Rosen.