in·cu·bus (ĭnkyə-bəs, ĭng-)
n. pl. in·cu·bus·es or in·cu·bi (-bī′)
1. An evil spirit supposed to descend upon and have sexual intercourse with women as they sleep.
2. A nightmare.
3. An oppressive or nightmarish burden.
[Middle English, from Late Latin, alteration of Latin incubō, from incubāre, to lie down on; see INCUBATE.]
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