Direct synonyms:
* Abandoned
* Empty
* Uninhabited
* Forsaken
* Unoccupied
* Solitary
Words with similar connotations:
* Desolate
* Bleak
* Barren
* Lonely
* Isolated
* Ghostly
* Silent
* Gloomy
The best word to use will depend on the specific context and the tone you want to convey.
For example, if you're describing a building, "abandoned" might be the best choice. If you're describing a landscape, "desolate" might be more appropriate. And if you're describing a feeling, "lonely" might be the most accurate.