Economic Definition of injection. Defined.
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Term injection Definition: A non-consumption expenditure on gross domestic product, including investment expenditures, government purchases, and exports. Injections are combined with leakages in the injection-leakage model used to identify equilibrium aggregate output in Keynesian economics. The notion of injection is best viewed through the circular flow, in which investment expenditures, government purchases, and exports are "injected" into the main flow between output, factor payments, national income, and consumption.