Marginal (economics)
Etymology
From “margin,” Latin “margo” (edge). The economic sense arose in the 1870s “marginalist revolution” of Jevons, Menger, and Walras, who located value at the margin — in the usefulness of the last unit consumed rather than the whole stock.
adjective · /MAR-jih-nuhl/
Relating to the effect of one more unit — the next hour, the next dollar, the next customer.
What it names
The frame nearly all good economic decisions use: not the total, but the change from doing a little more or less.
Example
A factory should add a shift only if the marginal revenue from the extra output beats the marginal cost of running it.
Related idea
Confusing marginal with average is a classic error: your marginal tax rate applies only to your next dollar of income, not to your whole salary, so a raise never lowers your take-home pay.
adjective · /MAR-jih-nuhl/
So small or minor as to be barely significant; on the edge of importance.
What it names
a low degree of importance or effect
Example
The new design made only a marginal difference to sales.
Related idea
The everyday sense — barely worth counting — sits alongside the economist’s “one more unit.” Compare tenuous and cursory.