'pro-Soviet' originates as a modern English compound formed in the 20th century from the prefix 'pro-' and the noun 'Soviet'. 'pro-' originates from Latin, specifically the word 'pro', where 'pro-' meant 'for'. 'Soviet' originates from Russian, specifically the word 'sovet', where 'sovet' meant 'council'.

'Soviet' entered English in the early 20th century (c. 1917) from Russian 'sovet' and became established as the name for councils and, by extension, the Bolshevik-led government ('Soviet Russia', later 'Soviet Union'). The English compound 'pro-Soviet' developed later to describe support for those councils/government/policies.

Initially, 'Soviet' referred to a 'council' and then to the political entities (the Soviet state); 'pro-Soviet' originally meant 'for or in favor of the Soviet state' and has remained largely consistent in meaning, denoting support or sympathy toward the Soviet Union or its policies.