Deficit

A deficit is the opposite of a surplus, meaning: more of something has gone out than been taken in.

When people speak of the the federal deficit, it refers to the amount of spending grossly outstripping the incoming tax revenues to pay for them. The mechanics, however, can apply to any metric, and can reference the deficit of rational discourse vs. personal invective, the deficit of books in print now vs. 10 years ago, and the deficit of decent tasting bagels west of the Mississippi vs. in NYC and Boston.