Practice Essentials. The term âpernicious anemiaâ is an anachronismâit dates from the era when treatment had not yet been discovered, and the disease was fatalâbut it remains in use for megaloblastic anemia resulting from vitamin B12 deficiency due to lack of intrinsic factor (IF).
The definition of a fan is  a person who is very enthusiastic about someone or something, or a device that moves and cools the air. An example of a fan is a person who only wears gold and red in support of the San Francisco 49ers. An example of a fan is an electrical device with moving blades that cools air.
Anything that a fan believes is implied, or just believes about the universe or characters is referred to as fanon. Both these elements are used in fan-fiction sometimes in order to create a new story that the fan wants to happen. There are also fan-fiction pieces that are called alternate universe fan-fiction, or AU for short.