upstairs

nouns

the part of a building above the ground floor
"no one was allowed to see the upstairs"
is a part of
a structure that has a roof and walls and stands more or less permanently in one place
"there was a three-story building on the corner"; "it was an imposing edifice"
is a type of (narrower)
something less than the whole of a human artifact
"the rear part of the house"; "glue the two parts together"

adjectives

on or of upper floors of a building
"the upstairs maid"; "an upstairs room"
antonym

adverbs

on a floor above
"they lived upstairs"
antonym
with respect to the mind
"she's a bit weak upstairs"