An Apocalypse is a disclosure of something hidden from the majority of mankind in an era dominated by falsehood and misconception, i.e. the veil

Calypsis

Calypsis ' is the act of covering, concealing, hiding, or veiling. In kinesics, the science of body language, calypsis is the act of covering or concealing certain parts of one's own body. Calypsis is a type of closed, negative or defensive body language used to express disapproval, discomfort or...

 to be lifted. The Apocalypse of John (Greek Ἀποκάλυψις Ἰωάννου) is the Book of Revelation

Book of Revelation

The Book of Revelation is the final book of the New Testament. The title came into usage from the first word of the book in Koine Greek: apokalupsis, meaning "unveiling" or "revelation"...

, the last book of the New Testament

New Testament

The New Testament is the second major division of the Christian biblical canon, the first such division being the much longer Old Testament....

. By extension, apocalypse can refer to any End Time scenario, or to the end of the world

Risks to civilization, humans and planet Earth

Various existential risks could threaten humankind as a whole, have adverse consequences for the course of human civilization, or even cause the end of planet Earth.-Types of risks:...

 in general.
The disclosure of future events is made through a dream, as was the experience for the prophet Daniel

Daniel

Daniel is the protagonist in the Book of Daniel of the Hebrew Bible. In the narrative, when Daniel was a young man, he was taken into Babylonian captivity where he was educated in Chaldean thought. However, he never converted to Neo-Babylonian ways...

, which is recorded in the book with his name, or a vision

Vision (religion)

In spirituality, a vision is something seen in a dream, trance, or ecstasy, especially a supernatural appearance that conveys a revelation.Visions generally have more clarity than dreams, but traditionally fewer psychological connotations...

 as was recorded by John of Patmos

John of Patmos

John of Patmos is the name given, in the Book of Revelation, as the author of the apocalyptic text that is traditionally cannonized in the New Testament...

 in the Book of Revelation

Book of Revelation

The Book of Revelation is the final book of the New Testament. The title came into usage from the first word of the book in Koine Greek: apokalupsis, meaning "unveiling" or "revelation"...

.