1834 New Ser. 1 39/2 Those..vehicles, that once rolled in slow and unupsettable solemnity along.
1922 W. S. Rainsford viii. 81 Good Red River carts.., unbreakable and almost un-upsettable.
2011 (Nexis) 1 July The focus at Wimbledon on Wednesday was Jo-Wilfried Tsonga's upset of the once un-upsettable Roger Federer.