fanon

noun5

1. •
   (slang) Elements introduced by fans which are not in the official canon of a fictional world but are widely believed to be or treated as if canonical.

   • In this way, smaller groups within a fandom agree on readings which may be completely at odds with the canon, but which in time acquire legitimacy as fanon. — 2014
2. •
   Part of a bishop's mitre. They are the tabs extending down from the mitre, often with a cross near the end of each. See lappet.
3. •
   A vestment reserved only for the Pope for use during a pontifical Mass.
4. •
   A maniple.
5. •
   A fold of linen laid under a splint.