in·cu·bus
| \ ˈiŋ-kyə-bəs
, ˈin-\
plural incubi\ ˈiŋ-kyə-ˌbī
, -ˌbē , ˈin- \
also incubuses
1
: an evil spirit that lies on persons in their sleep
especially
: one that has sexual intercourse with women while they are sleeping — compare succubus
3
: one that oppresses or burdens like a nightmare