/up"stairz"/ , adv., adj., n., pl. upstairs .
adv.
1. up the stairs; to or on an upper floor.
2. Informal. in the mind: to be a little weak upstairs.
3. to or at a higher level of authority: You may have to take the matter upstairs.
4. Mil. Slang. at or to a higher level in the air.
5. kick upstairs , to promote (a person) to a higher position, usually having less authority, in order to be rid of him or her.
adj.
6. Also, upstair . of, pertaining to, or situated on an upper floor: an upstairs window; an upstairs apartment.
n.
7. ( usually used with a sing. v. ) an upper story or stories; the part of a building or house that is above the ground floor: The upstairs of this house is entirely rented.
8. a higher command or level of authority: We can't take action till we have approval from upstairs.
[ 1590-1600; UP- + STAIRS ]