incubus

noun4

1. •
   An evil spirit supposed to oppress people while asleep, especially to have sex with women as they sleep.
2. •
   Any oppressive thing or person; a burden.

   • Again he felt the impulse of flight: but his body was a dry dead incubus that refused to obey his volition. — 1935
3. •
   A feeling of oppression during sleep, sleep paralysis; night terrors, a nightmare.

   • it increaseth fearful dreams, incubus, night-walking, crying out, and much unquietness […] . — 2001
4. •
   One of various of parasitic insects, especially subfamily Aphidiinae.