A tacit agreement between two or more groups, parties, nations etc., that are in fundamental disagreement or conflict, that they will not go to war. Coexistence is not quite the same as peace, because the parties remain wary of each other and often hostile, but they accept that widely different ideologies and social systems can exist without those differences alone being a cause for war. Coexistence was a phrase often used during the Cold War, when it was a preferable alternative to the U.S. and the Soviet Union incinerating the entire world in a nuclear holocaust.