Apocrypha

The word “apocryphal” is derived from the Greek word apokryphos, meaning “hidden”. The idea was that most books in the Bible were meant for everyone, but the content of some books was “hidden”, and only meant for the initiated. These books were called “apocryphal”. The apocrypha were said to contain secret knowledge. This knowledge was not intended for the masses, but for a selected group of those initiated in the lore.
Originally, the term “apocryphal” was a positive label. Later, the term was used to indicate the books that were not part of the canon, and so “apocryphal” became the opposite of “canonical”.