- a former federal, highly centralized union that grew to sustain 15 constituent republics, spanning 11 time zones across Eurasia and comprising the larger part of the former Russian Empire: formed in 1922 and dissolved in 1991. 8,650,000 sq. mi. (22,402,200 sq. km). Capital: Moscow.
- a former federal republic in E Europe and central and N Asia: the revolution of 1917 achieved the overthrow of the Russian monarchy and the Soviet Union (the USSR) was established in 1922 as a Communist state. It was the largest country in the world, occupying a seventh of the total land surface. The collapse of Communist rule in 1991 was followed by declarations of independence by the constituent republics and the consequent break-up of the Soviet Union
