s, ing-]
, -bus⋅es. | 1. | an imaginary demon or evil spirit supposed to descend upon sleeping persons, esp. one fabled to have sexual intercourse with women during their sleep. Compare succubus (def. 1). |
| 2. | a nightmare. |
| 3. | something that weighs upon or oppresses one like a nightmare. |

incubus in·cu·bus (ĭn'kyə-bəs, ĭng'-)
n. pl. in·cu·bus·es or in·cu·bi (-bī')
An evil spirit believed to have sexual intercourse with women as they sleep.
A nightmare.
An oppressive or nightmarish burden.