upstairs

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adverb Up the stairs.
• adverb To or on a higher floor.
• adverb To or at a higher level.
• adjective Of or located on an upper floor.
• noun The part of a building above the ground floor.

from The Century Dictionary.

• In or to an upper story: as, to go up-stairs.
• Pertaining or relating to an upper story or flat; being above stairs: as, an up-stairs room.
• noun An upper story; that part of a building which is above the ground floor.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Being above stairs.
• adverb Up the stairs; in or toward an upper story.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adverb Up the stairs; on a higher floor or level.
• adverb slang In the brain.
• adjective located higher up a building.
• adjective baseball a pitched ball that is high, and usually outside the strike zone

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adverb with respect to the mind
• adverb on a floor above
• adjective on or of upper floors of a building
• noun the part of a building above the ground floor