- Inside of, as opposed to at, the margin. Example: for a firm that is producing 100 units, marginal cost is the cost of the 101st unit, while inframarginal cost refers, usually only qualitatively and without a precise definition, to the cost of units 1,...,100.
- (written as Inframarginal)Whereas most microeconomics analyses phenomena at the margin, i.e. when there is a small change, positive or negative, in a variable and the consequential changes it induces elsewhere in a model of the economy, inframarginal values are those that lie at rates of consumption, production, etc. that are lower than the marginal rate. Thus, for example, consumer's surplus is the sum of the excess of value over cost of acquisition of all inframarginal units of consumption (those lower than the marginal rate).