In doing some research for a project today, I came across a great term I’d never seen: retcon. According to Wikipedia:

Retroactive continuity or retcon is the adding of new information to “historical” material, or deliberately changing previously established facts in a work of serial fiction. The change itself is referred to as a “retcon”, and the act of writing and publishing a retcon is called “retconning”. Retconning can be done either on-purpose, or accidentally, wherein a break in continuity is not noticed until later and is then blessed by later events.

The full article has many examples.

Many of my favorite TV shows and comic books have gone through significant retconning. The first thing that comes to mind is “Buffy the Vampire Slayer,” which not only gave Buffy a kid sister in the fifth season, but made the reconfiguration of the backstories a key plot point. It was almost a meta-retcon. Which is too much responsibility to pile on a word I’ve only known for about for 15 minutes.

Quick, someone wiki it: [[retcon]]