down ‧ fall /ˈdaʊnfɔːl $ -fɒːl/ BrE AmE noun [singular]
1 . complete loss of your money, moral standards, social position etc, or the sudden failure of an organization:
the scandal that led to the president’s downfall
2 . something that causes a complete failure or loss of someone’s money, moral standards, social position etc
be sb’s downfall
an addiction to gambling that proved to be her downfall