Back in the 80s, when all-out war between the superpowers was thought to be a remote but real possibility, pundits often referred to the potential for "nuclear armageddon." Today the word is still in use, mainly among scary Christian sects who predict a final, apocalyptic conflict.
The word armageddon is taken from Christian eschatology (eg Revelations 16:16) where it is the site of the ultimate battle foreseen between the forces of good and the forces of evil. The most widely accepted derivation of the name is that it is from the Hebrew, Har Megiddo, the mountain of Megiddo, referring to the 4,000-year-old settlement about 20 miles south-east of Haifa.
Megiddo was where King Josiah fell in battle against the Egyptians in the seventh century BCE. This is probably the origin of the association of Megiddo with war which is also found in Zechariah 12:11.
An alternative etymology of armageddon is Har Migdo, "God's fruitful mountain," which is taken to refer to Mount Zion. This would square with passages in the book of Joel (eg 2:1-3) which envisage this as the site of a great struggle between good and evil.
Either way, let's hope and pray that the world wakes up to the currently emerging nuclear threats before armageddon moves out of the lexicon of apocalyptic fanatics and into mainstream usage once again.