The term apocrypha is used with various meanings, including "hidden", "esoteric", "spurious", "of questionable authenticity", and "Christian texts that are not canonical".

The word is originally Greek (α) and means "those having been hidden away". Specifically, α is the neuter plural of απόκρυφος, a participle derived from the verb αποκρύπτω [infinitive: αποκρύπτειν], "to hide something away."

The general term is usually applied to the books that the Protestant Christian Church considered useful but not divinely inspired. As such, it is misleading in this sense to refer to the Gospel according to the Hebrews or Gnostic writings as apocryphal, because they would not be classified in the same category by orthodox believers. Non-canonical books are texts of uncertain authenticity, or writings where the work is seriously questioned. Given that different denominations have different beliefs about what constitutes canonical scripture, there are several versions of the apocrypha.

During 16th-century controversies about the biblical canon, the word acquired a negative connotation, and has become a synonym for "spurious" or "false". This usage usually involves fictitious or legendary accounts that are plausible enough to be commonly considered true.