The Russian Soviet Federative Socialist Republic (Russian: Российская Советская Федеративная Социалистическая Республика, transliterated as Rossiyskaya Sovetskaya Federativnaya Sotsialisticheskaya Respublika [RSFSR], Mandarin: 俄罗斯苏维埃联邦社会主义共和国), also called the Russian Soviet Federated Socialist Republic, the Russian SFSR and the RSFSR for short, is the largest and most populous republic of the Union of Sovereign Socialist Republics.