[short for `retroactive continuity', from the Usenet newsgroup rec.arts.comics] 1. n. The common situation in pulp fiction (esp. comics or soap operas) where a new story `reveals' things about events in previous stories, usually leaving the `facts' the same (thus preserving continuity) while completely changing their interpretation. For example, revealing that a whole season of "Dallas" was a dream was a retcon. 2. vt. To write such a story about a character or fictitious object. "Byrne has retconned Superman's cape so that it is no longer unbreakable." "Marvelman's old adventures were retconned into synthetic dreams." "Swamp Thing was retconned from a transformed person into a sentient vegetable."
[This term is included because it is a good example of hackish linguistic innovation in a field completely unrelated to computers. The word `retcon' will probably spread through comics fandom and lose its association with hackerdom within a couple of years; for the record, it started here. --ESR]
[1993 update: some comics fans on the net now claim that retcon was independently in use in comics fandom before rec.arts.comics. In lexicography, nothing is ever simple. --ESR]