(initial capital letter)Often Soviets. a governing official or person living in the Soviet Union: The Soviets have denied our charge. ... (initial capital letter) of the Soviet Union: a Soviet statesman.

Does Soviet have a capital S?

That definition is under "Soviet", with a capital S, since it is a proper noun.

Is soviet a common noun?

soviet used as a noun:

A form of governing council in the former Soviet Union. The main form of communist government at all levels in the Soviet Union imposed in the bolshevik October Revolution in the former imperial Russia.