Antonyms of adj downstairs

1 sense of downstairs

Sense 1
downstairs (vs. upstairs), downstair -- (on or of lower floors of a building; "the downstairs (or downstair) phone")

upstairs (vs. downstairs), upstair -- (on or of upper floors of a building; "the upstairs maid"; "an upstairs room")

Similarity of adj downstairs

1 sense of downstairs

Sense 1
downstairs (vs. upstairs), downstair -- (on or of lower floors of a building; "the downstairs (or downstair) phone")
       => ground-floor -- (on the floor closest to level with the ground; "the ground-floor entrance is kept locked")

Antonyms of adv downstairs

1 sense of downstairs

Sense 1
downstairs, down the stairs, on a lower floor, below -- (on a floor below; "the tenants live downstairs")
       Antonym of upstairs (Sense 1)
      => upstairs, up the stairs, on a higher floor -- (on a floor above; "they lived upstairs")

Synonyms of adv downstairs

1 sense of downstairs

Sense 1
downstairs, down the stairs, on a lower floor, below -- (on a floor below; "the tenants live downstairs")