An incubus is a male evil spirit that has sex with sleeping women. A succubus is a female evil spirit that has sex with sleeping men. Both mythological figures have origins in antiquity, and the words themselves come from Latin.
Each word has a pair of accepted plurals—incubuses and incubi for incubus, and succubuses and succubi for succubus. English reference books are inconsistent in their recommendations. But because we are using the words in English, the English plurals are fine, even if spell check says otherwise.
Succubus is far more common than incubus, perhaps reflecting some sexism that has been tied to the word. We won’t go into that here, but it should go without saying that succubus should be used with caution where there’s potential for readers to infer sexism. In fact, it’s probably best to avoid using the word beyond its original mythological sense.
Not special prosecutor Kenneth Starr, the book’s villain, who comes off as pure evil—not really a human being at all, more of an incubus. [Associated Press]
Pfeiffer plays Ingrid as a self-absorbed succubus, a steely beauty whose soft features can harden into fierce will and whose speeches of lone-wolf self sufficiency hide an emotional vulnerability. [Seattle Post-Intelligencer]
You’re probably thinking the quotes above reflect the world according to Dick Cheney, David Addington, John Yoo, or some similar Bush-era incubus. [National Review]
In a nutshell, she’s a succubus in a short leather skirt who drags her boy into an abyss of drug abuse and rock-star pretense that ultimately destroys them both. [News Review]