Incubus

In"cu*bus (?), n.; pl. E. Incubuses (#), L. Incubi (#). [L., the nightmare. Cf. Incubate.]

1. A demon; a fiend; a lascivious spirit, supposed to have sexual intercourse with women by night. Tylor.

The devils who appeared in the female form were generally called succubi; those who appeared like men incubi, though this distinction was not always preserved.
Lecky.

2. (Med.) The nightmare. See Nightmare.

Such as are troubled with incubus, or witch- ridden, as we call it.
Burton.

3. Any oppressive encumbrance or burden; anything that prevents the free use of the faculties.

Debt and usury is the incubus which weighs most heavily on the agricultural resources of Turkey.
J. L. Farley.