Wiktionary
n. (context politics English) The idea that nation-states should not interfere with the domestic affairs of other countries in order to avoid conflict.
Wikipedia
Peaceful coexistence was a theory developed and applied by the Soviet Union at various points during the Cold War in the context of primarily Marxist–Leninist foreign policy and was adopted by Soviet-influenced " Socialist states" that they could peacefully coexist with the capitalist bloc (i.e., non-socialist states). This was in contrast to the antagonistic contradiction principle that Communism and capitalism could never coexist in peace. The Soviet Union applied it to relations between the western world, particularly between the United States and NATO countries and the nations of the Warsaw Pact.
Debates over differing interpretations of peaceful coexistence were one aspect of the Sino-Soviet split in the 1950s and 1960s. During the 1960s and early 1970s, the People's Republic of China under the leadership of its founder, Mao Zedong, argued that a belligerent attitude should be maintained towards capitalist countries, and so initially rejected the peaceful coexistence theory as essentially Marxist revisionism.
However, their decision in 1972 to establish a trade relationship with the United States also saw China cautiously adopting a version of the theory to relations between itself and non-socialist countries. From that point through to the early 1980s and Socialism with Chinese characteristics, China increasingly extended its own peaceful coexistence concept to include all nations. Enver Hoxha also denounced this and turned against China as a result of China growing closer ties to the West such as 1972 Nixon visit to China and today Hoxhaist parties continue to denounce the concept of peaceful coexistence.
Peaceful coexistence, in extending itself to all countries and social movements tied to the USSR's interpretation of communism, quickly became modus operandi for many individual communist parties as well, encouraging quite a few, especially those in the developed world, to give up their long-term goal of amassing support for an armed, insurrectionist communist revolution and exchange it for more full participation in electoral politics.