marginala.[Cf. F. marginal.]1. Of or pertaining to a margin.()2. Written or printed in the margin; as, a marginal note or gloss.()3. At the lower limit; barely sufficient; as, of marginal utility.()n. (Economics) 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.()