Cuba. Cuba (kyo͞oˈbə, Span. ko͞oˈbä), officially Republic of Cuba, republic (2020 est. pop. 11,326,616), 42,804 sq mi (110,860 sq km), consisting of the island of Cuba and numerous adjacent islands, in the Caribbean Sea. Havana is the capital and largest city.. Land and People. Cuba is the largest and westernmost of the islands of the West Indies and lies …Web