marginal cost(n = noun.attribute) differential cost, incremental cost - the increase or decrease in costs as a result of one more or one less unit of output;
is a kind of cost, monetary value, price

   The increase in total cost of production as a result of producing one more unit of output; since certain ovrhead costs are fixed, the marginal cost is almost aways less than the total per-unit cost of production averaged over all units produced. [WordNet 1.5]

at any cost, average cost, borrowing cost, capital cost, carrying cost, cost, cost accountant, cost accounting, cost analysis, cost cutting, cost increase, cost ledger, cost of capital, cost of living, cost overrun, differential cost, distribution cost, fixed cost, handling cost, incremental cost, marginal, marginal cost of production, marginal placentation, marginal utility, marginal wood fern, marketing cost, operating cost, opportunity cost, production cost, replacement cost, reproduction cost, unit cost