The term 'PART OF USSR' can be summarized by two crossword solutions: SOVIET (6 letters) and Sov (3 letters). The SOVIET Union, commonly known as the USSR, was a socialist state that existed from 1922 to 1991. It was a single-party state governed by the Communist Party, with Moscow as its capital. The SOVIET Union was a union of 15 SOVIET republics, and its government and economy were highly centralized. The SOVIET Union was one of the world's two superpowers, along with the United States, and it was the largest country in the world by area.