This usage has its origin in the title given to the New Testament Apocalypse; which title was itself obtained, very naturally, from the opening words 'Aπōκάλυψις 'Iησōῦ Χριστōῦ (see above), in which the term "revelation" is of course used simply to describe the contents of the book, not as a literary designation. The name Apocalypse was then given to other writings of the same general character, of which many appeared at about this time.
From the second century, it was applied to a number of books, both Jewish and Christian, which show the same characteristic features. Besides the Apocalypse of John (thus named in some of the earliest of the Christian Fathers), the Muratorian fragment, Clement of Alexandria, and others mention an Apocalypse of Peter. Apocalypses of Adam and Abraham (Epiphanius) and of Elias (Jerome) are also mentioned; see, for example, the six titles of this kind in the "List of the 60 Canonical Books". The use of the Greek noun to designate writings belonging to a certain class of literary products is thus of Christian origin, the original norm of the class being the New Testament Revelation.