Sentence:  <WSD>fan fiction</WSD> - Sometimes improperly used to mean fan science fiction, that is, ordinary fantasy published in a fan magazine. Properly, the term means fiction about fans, or something about pros, and occasionally bringing in some famous characters stf stories. It may refer to real fans by name (Tucker nudged Brackney, who was nursing a "black eye"), or may be about types, especially Joe Fann. 
Meaning of the word marked with <WSD> tags:  Fiction about fans and fandom created by members of fandom.