Definition:

a demon assuming female form in order to have sexual intercourse with men in their sleep

About the Word:

A succubus is the female version of an incubus - a demon in male form who has sexual intercourse with sleeping females.

Originating in medieval European folklore, with similar beings in many cultures, succubi appear in modern fiction, video games, and South Park.

As a more practical insult, the word is also used figuratively, as in this Jezebel.com headline: "This Week In Tabloids: Courtney the Evil Succubus Maneater Will Devour Bachelor Ben."