1. To visit often; to frequent: They haunted the movie theaters at least twice a week.
2. To obsess the mind constantly until it is relieved by coming to a solution: Not knowing the meaning of the word haunted Harriet until she found its definition.
3. To be continually present in; to pervade: All of the terrible things that are happening in the world haunt a lot of people.
4. To inhabit, to visit, or to appear in the form of a ghost or other supernatural being: There were those who thought the old house was being haunted by ghosts because of the strange noises that the neighbors frequently heard late in the nights.

Pertaining to being sad or beautiful to such a degree that it is difficult to forget: The haunting sounds of the singer's voice could not be forgotten by many people in the audience.