1. having gained an advantage in some way that betokens success, esp. over rivals.
2. leading an opponent by one point or one scoring unit: The home team was one up on the visitors.
3. one each; tied at a score of one: The score was one up in the ninth inning.
4. Print. with only one reproduction of a form per sheet or on a given sheet: We must print this job one up.
5. Journalism. using one more column of space than of type.
[ 1920-25 ]