say it: uhp-STERZ
upstairs is an adverb, noun and adjective meaning "on a floor above". It carries 4 recorded senses.
with respect to the mind
“she's a bit weak upstairs”
the part of a building above the ground floor
“no one was allowed to see the upstairs”
on or of upper floors of a building
“the upstairs maid”
“an upstairs room”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for upstairs come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.