[up.stairs] adv (1596) 1: up the stairs: on or to a higher floor
2: to or at a high altitude or higher position "kicked ~ to company management"
3: in the head: intellectually "a little slow ~ --Tom Clancy"
[2]up.stairs adj (1782): situated above the stairs esp. on an upper floor "an ~ bedroom" [3]up.stairs n pl but sing or pl in constr (1842): the part of a building above the ground floor