Primitive accumulation, as described in the text, refers to the process through which economic surplus is extracted from agricultural sectors to fuel industrialization and urbanization. This includes methods such as agricultural price controls and taxation, which squeeze surplus from farming communities, and the displacement of peasants to create a free wage labor force for urban industries. It's a historical necessity for economic transformation, particularly in late-industrializing countries like India and China, where it remains incomplete despite a declining agricultural share in GDP.