meaning: the part of a building above the ground floor (noun)

example:no one was allowed to see the upstairs

meaning: on a floor above (adverb)

example:they lived upstairs

synonyms:up the stairs,

meaning: with respect to the mind (adverb)

example:she's a bit weak upstairs

meaning: on or of upper floors of a building (adjective)

example:the upstairs maid