Yiff

Yiff is defined as pornographic material involving anthropomorphic animal characters (generally known as "furries"). This is not especially common in fanfic as few continua involve such characters. Most yiff fiction is original fic produced by the furry community. When it shows up in fanfic, it is almost invariably in fandoms where the original work is aimed at children (eg Disney) as they are the most likely to feature anthropomorphs, and is in the majority of cases intended as mockery of the fandom rather than a serious fic.

May also be used to describe scenes involving non-anthropomorphic animals, such as those in Cho Chang's Desires or Celebrian.