Pronunciation: (in'kyu-bus, ing'-), [key]
—pl. -biPronunciation: (-bī"), [key] -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. Cf. succubus (def. 1).
2. a nightmare.
3. something that weighs upon or oppresses one like a nightmare.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.