cataclysm

A cataclysm is a massive and extreme event that causes huge damage or destruction. It's like a massive storm or an earthquake that leaves things in ruins.

The word "cataclysm" gets used a lot in science fiction movies and books, but it also shows up in the news when there are big disasters. For example, if a volcano erupts and destroys a town, people might call it a cataclysm. In history class, you might learn about a great flood that was considered a cataclysm for its time. The word is often used to describe an event that's so big and devastating that it changes things forever.