ὑπερῷονhyperōion

a higher part of the house, i.e. apartment in the third story

Greek (New Testament) · G5253

Meanings

1. in classical Greek, the upper story or upper rooms where the women resided (Hom., a1.).

2. In LXX and NT, an upper chamber, roof-chamber, built on the flat roof of the house: Acts 1:13, Acts 9:37, Acts 9:39, Acts 20:8 (cf. 2 Kings 23:22).

Appears 4 times in the Bible.

Acts 1:13 When they arrived, they went to the upstairs room of the house where they were staying. Here are the names of those who were present: Peter, John, James, Andrew, Philip, Thomas, Bartholomew, Matthew, James (son of Alphaeus), Simon (the zealot), and Judas (son of James).
Acts 9:37 About this time she became ill and died. Her body was washed for burial and laid in an upstairs room.
Acts 9:39 So Peter returned with them; and as soon as he arrived, they took him to the upstairs room. The room was filled with widows who were weeping and showing him the coats and other clothes Dorcas had made for them.
Acts 20:8 The upstairs room where we met was lighted with many flickering lamps.

Source: G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922), public domain.