What's a word to describe an apartment when its owners are on vacation?
Solution 1:
I would use the word unattended, as opposite to attended.
From the Vocabulary.com Dictionary:
having a caretaker or other watcher
When I went on vacation, thieves climbed into my unattended apartment.
Solution 2:
I'd use vacant.
- having no occupant; unoccupied: no vacant seats on this train.
- not in use: a vacant room.