1. (adjective) on or of lower floors of a building

• downstair

2. (adverb) on a floor below

• below
• down the stairs
• on a lower floor

1. (adjective) on or of lower floors of a building

• ground-floor

1. (adjective) on or of lower floors of a building

• upstair
• upstairs

2. (adverb) on a floor below

• on a higher floor
• up the stairs
• upstairs