Noun: Phantasm (FAN-taz-um)
1. A product of fantasy.
2. A delusive appearance or illusion.
3. A ghost or specter.
4. A figment of the imagination.
5. A mental representation of a real object.
Sample sentence: The old mansion, which according to local legend is inhabited by the phantasm of an 18th-century resident, is the perfect location for a Halloween haunted house.