domino effect

Definitions

1. The situation in which one event sets off a chain of additional events.
2. The theory that, if South Vietnam became communist, it would be followed by Cambodia, Laos, additional Southeast Asian countries, other Asian countries, and likely even elsewhere.
   historical

Equivalents

Examples

“While the move⟳ has, for now, calmed fears of a repeat⟳ of a 2008-style domino effect, the merger has left Switzerland with a new megabank on Paradeplatz square.”

CEFR level