diminishing returns

noun

1. any rate of profit, production, benefits, etc., that beyond a certain point fails to increase proportionately with added investment, effort, or skill.
2. Also called law of diminishing returns. Economics. the fact, often stated as a law or principle, that when any factor of production, as labor, is increased while other factors, as capital and land, are held constant in amount, the output per unit of the variable factor will eventually diminish.

pl n economics

1. progressively smaller rises in output resulting from the increased application of a variable input, such as labour, to a fixed quantity, as of capital or land
2. the increase in the average cost of production that may arise beyond a certain point as a result of increasing the overall scale of production