It's meant to be up/top, as in 'this side facing up', but I did it by google translate because it's a new feature in v1.1 and so it wasn't in the original translations list (and unfortunately I didn't get suggestions when I asked about it elsewhere). Whatever the word is, it has to be 5 characters or less.
(The doubling cube's a record of the size of the current game's wager, and it's turned up to the next-higher side (so 2-4-8...) when the wager's doubled.)