Sentence:  Thus in Prokofieff the <WSD>Union</WSD> of Soviet Socialist Republics produced one of the great composers of the Twentieth Century . 
Meaning of the word marked with <WSD> tags:  a former communist country in eastern Europe and northern Asia; established in 1922; included Russia and 14 other soviet socialist republics (Ukraine and Byelorussia and others); officially dissolved 31 December 1991