Wiktionary
overbooking
n. An instance of selling or guaranteeing more seats than are available. vb. (present participle of overbook English)
Usage examples of "overbooking".
Once when Sharon had an overbooking, I had her send a couple of clients Georgie's way.
But the overbooking meant that what should have been Walter's seat would be occupied by someone else.
Months later, I saw on 60 Minutes that O'Hare is the world's worst for overbooking their runways.