CCCP Definition

abbreviation

Union of Soviet Socialist Republics.

Webster's New World

USSR; Union of Soviet Socialist Republics.

Wiktionary

Origin of CCCP

From Russian СССР (SSSR), abbreviation of Союз Советских Социалистических Республик (Sojúz Sovétskix Socialistíčeskix Respúblik, “The Union of Soviet Socialist Republics”).

From Wiktionary
Russ, USSR < Sojuz Sovetskix Socialističeskix Respublik; Russ C, P = English letters S, R

From Webster's New World College Dictionary, 5th Edition