The lyrics of a popular song from the 1980’s by the band REM go, “It’s the end of the world as we know it.” This song’s tune may be catchy but the sentiment is rather apocalyptic — since it refers to the final destruction of the world.
The base word of apocalyptic, apocalypse, means "ultimate doom." This scenario is most famously described in the Bible’s Book of Revelation, but the concept is used in reference to many extreme catastrophes. For example, the devastating conditions left behind after a hurricane or tornado has hit an area can be said to be apocalyptic. Often, this adjective is used for exaggeration, so you could also use apocalyptic to describe the bad haircut you just got.