unoccupied
adj.not having anyone in it or using it. You use this to describe a room, a seat, or a space that is empty.
adj.not containing, holding, or being used by anyone or anything. Often used to describe physical spaces or vehicles that are currently empty.
“The seat next to me is unoccupied.”
“The hotel staff checked the unoccupied rooms to ensure that all the lights were turned off before leaving for the night.”
“The pilot reported that the aircraft was unoccupied and that the emergency lights were flashing as a warning to the ground crew.”
“All vehicles were unoccupied at the time and no vehicles were stolen.”
“It is unclear how many of the 143 properties rated F or G are unoccupied while they are being renovated or sold.”
From Middle English unoccupied; equivalent to un- + occupied.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.