domino theory

/ˈdɑməˌnoʊ ˈθɪri/

The domino theory is the idea that if one thing falls, a lot more things will fall, too, like a line of dominoes. It’s also the political idea that if one nation “falls” to communism, neighboring countries will follow.

The concept behind the domino theory imagines neighboring countries falling, one by one, like dominoes, under the influence of a political ideology or event. Starting in the 1950s, the United States became concerned about the spread of communism, and President Eisenhower first mentioned his domino theory in 1954. This theory was mentioned by successive politicians through the 1980s. If you’re not talking about politics, the domino theory can refer to anything that causes a chain reaction.

Definitions of domino theory

1. noun

   the political theory that if one nation comes under communist control then neighboring nations will also come under communist control
   type of:

   ideology, political orientation, political theory

   an orientation that characterizes the thinking of a group or nation