suc ‧ cu ‧ bus /ˈsʌkjəbəs, ˈsʌkjʊbəs/ BrE AmE noun ( plural succubi /-baɪ/) [countable]
[ Date: 1300-1400 ; Language: Medieval Latin ; Origin: Late Latin succuba 'prostitute' , from Latin succubare 'to lie under' , from sub- ( ⇨ ↑ sub- ) + cubare 'to lie' ]
a female devil that in the past was believed to have sex with a sleeping man