Main entry: upstair, upstairs
Definition: on or of upper floors of a building
Usage: the upstairs maid; an upstairs room
Antonyms: downstair, downstairs
Definition: on or of lower floors of a building
Main entry: on a higher floor, up the stairs, upstairs
Definition: on a floor above
Usage: they lived upstairs
Antonyms: down the stairs, downstairs, on a lower floor, below
Definition: on a floor below