Initially used to refer to an exactly 100 word work, it now refers to any short fanfic.
a single scene, usually a wallow scene, written without the frame of a story; used mostly in on-line slash fiction
100 word fic. no more, no less. unless it's a half-drabble (50 words), a double-drabble (200) or some other such concoction. or an almost-drabble.