downfall
A precipitous decline in fortune; death or rapid deterioration, as in status or wealth.
Example
“Many economic and political reasons led to the downfall of the Roman Empire.”
Other meanings
The cause of such a fall; a critical blow or error.
An act of falling down.
“a downfall of rain”
Where this comes from
This definition is adapted from “downfall” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.