Liberal Dictionary English Dictionary
noun
- a theory that if one country is taken over by an expansionist, especially Communist, neighbor, party, or the like, the nearby nations will be taken over one after another.
in geo-politics, by 1963; see domino. Eisenhower’s original phrase was domino principle (1954).
The idea that if one key nation in a region fell to control of communists, others would follow like toppling dominoes. The theory was used by many American leaders to justify American intervention in the Vietnam War. (See policy of containment.)