蘇維埃社會主義共和國聯盟（俄語：Союз Советских Социалистических Республик，羅馬化：Soyuz Sovetskikh Sotsialisticheskih Respublik（ⓘ），縮寫：СССР），簡稱蘇聯[註 1]，又稱蘇維埃社會主義共和國聯邦[註 2]，是1922年至1991年間存在於歐洲及亞洲的聯邦制社會主義國家，其領土涵蓋東歐大部分區域，以及幾乎整個中亞和北亞；最大疆域面積超過2,240萬平方公里，跨越11個時區，是當時世界上領土面積最大的國家。蘇聯依據《蘇聯憲法》規定實行聯邦制，由15個權利平等的蘇維埃社會主義共和國按照自願聯合的原則組成。不過，蘇聯中央政府權力高度集中，其聯邦性質並不顯著。蘇聯由蘇聯共產黨一黨執政，是世界上第一個完全實施社會主義制度及計劃經濟政策的國家[4][5]。 The Soviet Union,[n] officially the Union of Soviet Socialist Republics[o][p] (USSR),[q] was a transcontinental country that spanned much of Eurasia from 1922 until its dissolution in 1991. It was the world's third-most populous country, the largest by area, and bordered twelve countries.[r] A diverse multinational state, it was organized as a federal union of national republics, with the largest and most populous being the Russian Soviet Federative Socialist Republic (SFSR).[s] In practice, its government and economy were highly centralized. As a one-party state governed by the Communist Party, it was the flagship communist state. Its capital and largest city was Moscow.
